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| 2. |
- Brittebo, Eva, 1951-, et al.
(författare)
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Bioactivation and effects of environmental pollutants in human and rodent blood vessel endothelial cells
- 2012
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Ingår i: Organohalogen compound database (http://www.dioxin20xx.org/ohc_database_search.htm).
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Konferensbidrag (refereegranskat)abstract
- IntroductionRecent epidemiological studies reveal associations between exposure to environmental pollutants and cardiovascular disorders in humans. Elevated serum concentrations of polychlorinated biphenyls (PCBs) have for instance been associated with cardiovascular risk factors such as hypertension (1-3). Exposure to the carbonate plastic monomer bisphenol A (BPA) has been associated with an increased incidence of cardiovascular disease and atherogenic changes in the vascular wall (4-6). The contention that the human cardiovascular system is a sensitive target for toxic chemicals gain support from our earlier and recent experimental studies in rodents, birds and fish, as well as in cultured human primary endothelial cells. It is also compatible with earlier observations that certain polycyclic aromatic hydrocarbons (PAHs) are environmental carcinogens that may also contribute to atherosclerosis in mice and birds (7,8).In this presentation we will briefly discuss effects of Ah receptor (AhR) agonists (e.g. the coplanar PCB126 or BNF, ß-naphthoflavone) on the expression of cytochrome P450 (CYP)1 enzymes in various endothelia in rodents in vivo or ex vivo, as well as in cultured human umbilical vein endothelial cells (HUVEC). The CYP1-dependent bioactivation and irreversible binding of prototype polyaromatic hydrocarbons (PAH) and heterocyclic amines such as benzo(a)pyrene (BaP), 7,12-dimethyl- benz(a)anthracene (DMBA) and 3-amino-1,4-dimethyl-5H-pyrido- [4,3-b]indole (Trp-P1) in these endothelia will be reviewed. We will also report how PCB126 affects vasoactive factors in HUVEC, and how these effects are modulated by physiological 17ß-oestradiol concentrations. Some effects of PCB126, 1-nitropyrene (1-NP) and bisphenol A (BPA) on biomarkers for endothelial dysfunction, cell stress and DNA damage in HUVEC will finally be presented.Material and methodsHuman umbilical vein endothelial cells (HUVEC) were purchased from Science Cell Research laboratories, Carlsbad, CA. C57Bl mice and Wistar or Sprague Dawley rats were purchased from various suppliers. All animal experiments were approved by the Local Ethical Committee for Research on Animals in Uppsala and the studies followed the guidelines laid down by the Swedish and European Union legislation on animal experimentation. Rodents, tissue-slices and cultured cells were treated with model chemicals as previously described. Tape section and light microscopy autoradiographic imaging using 3H-labelled BaP, DMBA and Trp-P-1 and immunohistochemistry was performed as previously described (9-19). Precision-cut tissue slices for in vitro autoradiography were prepared as described in (14) and the slices were incubated with various 3H-labelled chemicals. HUVEC were exposed to various compounds and the detection of biomarkers of endothelial dysfunction, DNA damage were performed as described (20-22). Finally, female Fischer rats were exposed to BPA (0.025, 0.25 and 2.5 mg/l) and fructose (50 g/l) in the drinking water from 5 to 15 weeks of age to mimic human exposure (unpublished data).Results and discussionCo-localization of CYP1A1 expression and BaP, DMBA and Trp-P-1 adduct formation in endothelial linings As demonstrated by immunohistochemistry, a high CYP1A immunoreactivity occurred in capillaries of the heart, skeletal muscle, uterus and in blood-brain interfaces such as the leptomeninges and plexus choroideus, whereas no expression was observed for instance in cerebral capillary endothelial cells of mice treated with AhR agonists (9-11). No, or very low constitutive immunoreactivities were observed in these endothelia in vehicle-treated animals. No basal or induced CYP1B1 expression was observed in endothelial cells, while a weak CYP1B1 immunostaining was detected in the muscle layer of small arteries. It should be noted that in subcellular preparations of whole organs, e.g. heart and brain, the CYP1A1 in endothelial cells is diluted due to cells that do not express high levels of CYP1A1, for examples myocytes or neurons, in excess. A cell-specific metabolism in endothelial cells may therefore remain undetected due to the presence of metabolically inactive cells. In order to detect minor sites of bioactivation such as endothelial linings we employed light microscopic autoradiographic imaging to examine the bioactivation and subsequent irreversible binding of the radiolabelled prototype toxicants in tissues of animals pretreated with AhR-agonists. As determined by light microscopic autoradiography of AhR-agonist-treated mice exposed to 3H-labelled BaP, DMBA or Trp-P-1 and birds exposed to 3H-Trp-P-1 a significant accumulation of non-extractable radioactivity occurred in endothelial linings (9-18). The bound radioactivity occurred in the nuclei and the perinuclear cytoplasm, suggesting that the autoradiograms depict both DNA- and protein-bound adducts. Since the binding sites of 3H-labelled BaP, DMBA or Trp-P-1 corresponded with the sites of CYP1A1 induction, we concluded that rodents express a constitutively low but highly inducible and functional CYP1A1 in endothelial cells. The binding of reactive metabolites in endothelial cells exceeded the binding in all other cell types in AhR-agonist treated mice and was abolished by pretreatment with the CYP1A1 inhibitor ellipticine, supporting a CYP1A1-catalysed metabolic activation in situ to a reactive species (9, 10,12). These findings imply that there is a preferential CYP1A1-catalysed formation of reactive metabolites from all three carcinogens in endothelial cells expressing high CYP1A1 levels. Interestingly, however, carcinogenesis in endothelial cells is a relative rare finding, suggesting that degenerative lesions and cell death may be more prevalent responses to metabolism-activated carcinogens/mutagens in these cells. Experiments with 3H-DMBA and 3H-Trp-P-1 in HUVEC confirmed that AhR-agonists induced an increased bioactivation, suggesting that also human endothelial cells should be targets for toxicity of reactive intermediates formed from CYP1A1- activated carcinogens/mutagens (17-18). This conclusion is supported by immunohistochemical studies on the heavily vascularized human endometrium demonstrating an expression of CYP1A1 and CYP1B1 protein in and around human endometrial blood vessels, although a large interindividualvariation was observed (19). None of the endometrial biopsy samples displayed vascular expression of CYP2A6, CYP2B6, CYP2C8/2C9/2C19, CYP2D6, or CYP3A4/5 protein.Effects of PCB 126, 1-NP, and BPA on biomarkers of endothelial dysfunction and cell stress in endothelial cells In vitro studies demonstrated that PCB126 increased the levels of vasoconstriction factors and decreased the levels of vasodilating factors in cultured HUVEC in a fashion that is characteristic for endothelial dysfunction related to human hypertension. The study showed that the co-planar PCB126 induced expression of the endothelium-derived vasoconstriction factor COX-2 and stimulated formation of the vasoconstrictor prostaglandin PGF2 via the AhR in HUVEC (20). COX-2 is known to play a role in hypertension by catalysing the formation of vasoconstriction prostaglandins and by stimulating reactive oxygen species (ROS) production. Further studies demonstrated that PCB126 increased the production of the vasoconstriction prostaglandin PGF2 and ROS in HUVEC. The relationship between increased ROS production and human hypertension is well established, ROS promotes vasoconstriction by stimulating the production of vasoconstriction prostaglandins and by reducing bioavailability of the vasorelaxing factor NO. Indeed, exposure to PCB126 slightly reduced the production of NO in HUVEC. Furthermore, the PCB126-induced mRNA expressions of CYP1A1, CYP1B1 and COX-2 in HUVEC were enhanced in the presence of physiological levels of 17- estradiol. This suggests that increased levels of oestrogen stimulate AhR-dependent transcription of genes previously associated with endothelial dysfunction and hypertension.In another study we have examined the effects of a nitrated PAH, 1-nitropyrene, that is abundant in diesel exhausts (21). The results revealed that 1-NP induced DNA damage, increased levels of ROS and increased protein expression of the endoplasmic reticulum stress chaperone GRP78 in cultured HUVEC. Induction of CYP1A1 by PCB126 as well as inhibition of nitroreductive metabolism by dicoumarol attenuated the induction of DNA damage, intracellular ROS levels and GRP78 expression. This suggests that the effects of 1-NP on HUVEC were mediated by metabolites mainly formed at nitroreduction and not by CYP1-dependent bioactivation to reactive intermediates.Recent in vitro studies demonstrated that bisphenol A increased the mRNA expression of genes that regulate vasoconstriction and angiogenesis in HUVEC (eNOS, VEGF, VEGFR2, connexin 43 and ACE1) and in human cardiomyocytes (eNOS and ACE1) (22). The results also showed that BPA increased the expression of P-eNOS(ser1177) and the production of NO in HUVEC. NO is the main effector molecule in angiogenesis downstream of VEGF. Based on the findings that BPA increase the expression of proangiogenic factors we investigated whether BPA could stimulate in vitro angiogenesis in HUVEC using the endothelial tube formation assay. The results demonstrated that BPA increased HUVEC tube formation suggesting that BPA can act directly on the endothelium and stimulate angiogenesis. Long-term exposure in rats revealed that environmentally relevant levels of BPA, increased the cardiac mRNA expression of genes that regulate vasoconstriction and angiogenesis. Ten weeks exposure of rats from preadolescence to adulthood to BPA in the drinking water increased theexpression of eNOS, VEGF, VEGFR2 and ACE1 in the heart. Taken together, the genes that were upregulated in rat cardiac tissues in vivo were also upregulated in human endothelial cells and cardiomyocytes in vitro. The heart is a heavily vascularized t
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| 3. |
- Klint, Helén, et al.
(författare)
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Low-dose exposure to bisphenol A in combination with fructose increases expression of genes regulating angiogenesis and vascular tone in juvenile Fischer 344 rat cardiac tissue
- 2017
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 122:1, s. 20-27
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Epidemiological studies report associations between exposure to the high-volume chemical and endocrine disruptor bisphenol A (BPA) and cardiovascular disorders, but there is a lack of experimental studies addressing the mechanisms of action of BPA on the cardiovascular system. In the present study, effects on markers for cardiovascular function of exposure to BPA and fructose in vivo in rat cardiac tissues, and of BPA exposure in human cardiomyocytes in vitro, were investigated.MATERIALS: Juvenile female Fischer 344 rats were exposed to 5, 50, and 500 μg BPA/kg bodyweight/day in their drinking water from 5 to 15 weeks of age, in combination with 5% fructose. Further, cultured human cardiomyocytes were exposed to 10 nM BPA to 1 × 10(4) nM BPA for six hours. Expression of markers for cardiovascular function and BPA target receptors was investigated using qRT-PCR.RESULTS: Exposure to 5 μg BPA/kg bodyweight/day plus fructose increased mRNA expression of Vegf, Vegfr2, eNos, and Ace1 in rat heart. Exposure of human cardiomyocytes to 1 × 10(4) nM BPA increased mRNA expression of eNOS and ACE1, as well as IL-8 and NFκβ known to regulate inflammatory response.CONCLUSIONS: . Low-dose exposure of juvenile rats to BPA and fructose induced up-regulation of expression of genes controlling angiogenesis and vascular tone in cardiac tissues. The observed effects of BPA in rat heart were in line with our present and previous studies of BPA in human endothelial cells and cardiomyocytes. These findings may aid in understanding the mechanisms of the association between BPA exposure and cardiovascular disorders reported in epidemiological studies.
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| 5. |
- Lejonklou, Margareta Halin, 1966-, et al.
(författare)
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Effects of Low-Dose Developmental Bisphenol A Exposure on Metabolic Parameters and Gene Expression in Male and Female Fischer 344 Rat Offspring.
- 2017
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Ingår i: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 125:6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Bisphenol A (BPA) is an endocrine-disrupting chemical that may contribute to development of obesity and metabolic disorders. Humans are constantly exposed to low concentrations of BPA, and studies support that the developmental period is particularly sensitive.OBJECTIVES: The aim was to investigate the effects of low-dose developmental BPA exposure on metabolic parameters in male and female Fischer 344 (F344) rat offspring.METHODS: Pregnant F344 rats were exposed to BPA via their drinking water, corresponding to (BPA0.5; ) or (BPA50; ), from gestational day (GD) 3.5 until postnatal day (PND) 22, and controls were given vehicle (). Body weight (BW), adipose tissue, liver (weight, histology, and gene expression), heart weight, and lipid profile were investigated in the 5-wk-old offspring.RESULTS: Males and females exhibited differential susceptibility to the different doses of BPA. Developmental BPA exposure increased plasma triglyceride levels ( compared with , females BPA50 ; compared with , males BPA0.5 ) in F344 rat offspring compared with controls. BPA exposure also increased adipocyte cell density by 122% in inguinal white adipose tissue (iWAT) of female offspring exposed to BPA0.5 compared with controls ( number of adipocytes/HPF compared with number of adipocytes/HPF; ) and by 123% in BPA0.5 females compared with BPA50 animals ( number of adipocytes/high power field (HPF) compared with number of adipocytes/HPF; ). In iWAT of male offspring, adipocyte cell density was increased by 129% in BPA50-exposed animals compared with BPA0.5-exposed animals ( number of adipocytes/HPF compared with number of adipocytes/HPF; ). Furthermore, the expression of genes involved in lipid and adipocyte homeostasis was significantly different between exposed animals and controls depending on the tissue, dose, and sex.CONCLUSIONS: Developmental exposure to of BPA, which is 8-10 times lower than the current preliminary EFSA (European Food Safety Authority) tolerable daily intake (TDI) of and is within the range of environmentally relevant levels, was associated with sex-specific differences in the expression of genes in adipose tissue plasma triglyceride levels in males and adipocyte cell density in females when F344 rat offspring of dams exposed to BPA at were compared with the offspring of unexposed controls.
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| 6. |
- Lind, Lars, et al.
(författare)
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Brachial artery intima-media thickness and echogenicity in relation to lipids and markers of oxidative stress in elderly subjects : --the prospective investigation of the vasculature in Uppsala Seniors (PIVUS) Study.
- 2008
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Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 43:2, s. 133-41
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to relate brachial artery intima-media thickness (IMT) and the grey scale median of the intima-media complex (IM-GSM) to traditional cardiovascular risk factors and markers of inflammation and oxidative stress. In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, a population-based study of 1016 subjects aged 70, brachial artery IMT and IM-GSM, who were evaluated by ultrasound. Lipids, thirteen markers of inflammation and nine markers of oxidative stress were measured. The Framingham risk score was related to IMT (p < 0.0001), but not to the IM-GSM. In univariate analysis, HDL-cholesterol, serum triglycerides, fasting glucose, smoking, HOMA insulin resistance index and oxidized LDL levels were related to IMT. HDL and LDL-cholesterol, triglycerides, VCAM-1, e-selectin, leukocyte count, conjugated diens, baseline conjugated diens (BCD)-LDL, antibodies to oxLDL, the GSSG/GSH glutathione ratio and homocysteine were related to IM-GSM. In multiple regression models, HDL-cholesterol, fasting glucose and oxLDL levels were the independently related to IMT (p = 0.01-0.04), while serum triglycerides, BCD-LDL and the GSSG/GSH ratio were independently related to IM-GSM (p = 0.0001-0.004). In conclusion, in addition to traditional lipid variables, markers of oxidative stress were associated with both thickness and echogenicity of the brachial artery intima-media complex. Thus, both thickness and echogenicity of the brachial artery intima-media complex might be useful biomarkers in the future.
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| 7. |
- Lind, Lars, et al.
(författare)
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The echogenecity of the intima-media complex in the common carotid artery is closely related to the echogenecity in plaques.
- 2007
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Ingår i: Atherosclerosis. - : Elsevier BV. - 0021-9150 .- 1879-1484. ; 195:2, s. 411-414
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Tidskriftsartikel (refereegranskat)abstract
- Objective The echogenecity measured by ultrasound of atherosclerotic plaques is related to future cardiovascular events. The aim of the present study is to relate the grey scale median of the intima–media complex (IM-GSM) of the common carotid artery (CCA) to the echogenecity of carotid plaques. Material and results In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, a population-based study of 1016 subjects aged 70, carotid artery intima–media thickness (IMT) and IM-GSM were evaluated by ultrasound and computerized analysis. Also the occurrence of plaque and plaque GSM were measured. The echogenecity of the plaques was also visually estimated by the Gray-Weale classification. In subjects with a carotid plaque (n=582), IM-GSM in CCA was correlated to GSM in the plaque (r=0.60, p<0.0001) independently of plaque size and IMT. IM-GSM in CCA was also correlated to the visually estimated echogenecity (p<0.0001 for trend). Conclusion IM-GSM of the CCA is closely related to the echogenecity in overt carotid plaques, regardless if evaluated by the same computerized method or evaluated visually. This finding suggests that IM-GSM of CCA could be an important and easily measurable characteristic of the carotid artery wall that could be obtained in almost all subjects and not only those with an overt plaque.
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| 9. |
- Lind, Monica, et al.
(författare)
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Subclinical hypervitaminosis A in rat : measurements of bone mineral density (BMD) do not reveal adverse skeletal changes
- 2006
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Ingår i: Chemico-Biological Interactions. - : Elsevier BV. - 0009-2797 .- 1872-7786. ; 159:1, s. 73-80
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that subclinical hypervitaminosis A in rats causes fragile bones. To begin to investigate possible mechanisms for Vitamin A action we extended our previous study. Forty-five mature female Sprague-Dawley rats were divided into three groups, each with 15 animals. They were fed a standard diet containing 12IU Vitamin A per g pellet (control, C), or a standard diet supplemented with 120 IU ("10xC") or 600 IU ("50xC") Vitamin A/g pellet for 12 weeks. At the end of the study, serum retinyl esters were elevated 4- and 20-fold. Although neither average food intake nor final body weights were significantly different between groups, a dose-dependent reduction in serum levels of Vitamin D and E, but not Vitamin K, was found. In the 50xC-group the length of the humerus was the same as in controls, but the diameter was reduced (-4.1%, p<0.05). Peripheral quantitative computed tomography (pQCT) at the diaphysis showed that bone mineral density (BMD) was unchanged and that periosteal circumference had decreased significantly (-3.7%, p<0.05). Ash weight of the humerus was not affected, but since bone volume decreased, volumetric BMD, as measured by the bone ash method, even increased (+2.5%, p<0.05). In conclusion, interference with other fat-soluble Vitamins is a possible indirect mechanism of Vitamin A action. Moreover, BMD measurements do not reveal early adverse skeletal changes induced by moderate excesses of Vitamin A in rats. Since the WHO criterium for osteoporosis is based on BMD, further studies are warranted to examine whether this is also true in humans.
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| 10. |
- Lind, P. Monica, et al.
(författare)
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Serum concentrations of phthalate metabolites are related to abdominal fat distribution two years later in elderly women
- 2012
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Ingår i: Environmental Health. - 1476-069X. ; 11:1, s. 21-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Phthalates, commonly used to soften plastic goods, are known PPAR-agonists affecting lipid metabolism and adipocytes in the experimental setting. We evaluated if circulating concentrations of phthalates were related to different indices of obesity using data from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Data from both dual-energy X-ray absorptiometry (DXA) and abdominal magnetic resonance imaging (MRI) were used.METHODS: 1,016 subjects aged 70 years were investigated in the PIVUS study. Four phthalate metabolites were detected in the serum of almost all subjects (> 96%) by an API 4000 liquid chromatograph/tandem mass spectrometer. Abdominal MRI was performed in a representative subsample of 287 subjects (28%), and a dual-energy X-ray absorptiometry (DXA)-scan was obtained in 890 (88%) of the subjects two year following the phthalate measurements.RESULTS:In women, circulating concentrations of mono-isobutyl phthalate (MiBP) were positively related to waist circumference, total fat mass and trunk fat mass by DXA, as well as to subcutaneous adipose tissue by MRI following adjustment for serum cholesterol and triglycerides, education, smoking and exercise habits (all p < 0.008). Mono-methyl phthalate (MMP) concentrations were related to trunk fat mass and the trunk/leg-ratio by DXA, but less powerful than MiBP. However, no such statistically significant relationships were seen in men.CONCLUSIONS:The present evaluation shows that especially the phthalate metabolite MiBP was related to increased fat amount in the subcutaneous abdominal region in women measured by DXA and MRI two years later.
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