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- Herlin, Maria, et al.
(författare)
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Inhibitory effects on osteoblast differentiation in vitro by the polychlorinated biphenyl mixture Aroclor 1254 are mainly associated with the dioxin-like constituents.
- 2015
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Ingår i: Toxicology in Vitro. - : Elsevier BV. - 1879-3177 .- 0887-2333. ; 29:5, s. 876-883
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Tidskriftsartikel (refereegranskat)abstract
- The polychlorinated biphenyl (PCB) mixture Aroclor 1254 alters bone tissue properties. However, the mechanisms responsible for the observed effects have not yet been clarified. This study compared the effect of Aroclor 1254 on the expression of osteoblast differentiation markers in MC3T3-E1 cells with the corresponding effect of the dioxin reference compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and two PCB congeners belonging to the category of non-dioxin-like PCBs. The aim of the study was to quantify the relative influence of dioxin-like and non-dioxin-like PCB-components on osteoblast differentiation. Expression of marker genes for AhR activity and osteoblast differentiation were analyzed, and relative potency (REP) values were derived from Benchmark concentration-effect curves. Expression of alkaline phosphatase and osteocalcin were decreased by both Aroclor 1254 and TCDD exposure, while the PCB-congeners PCB19 and PCB52 slightly induced the expression. The relative potency of Aroclor 1254 for inhibitory effects on osteoblast differentiation marker genes was within the expected range as estimated from the chemical composition of Aroclor 1254. These results are consistent with previously observed bone modulations following in vivo exposure to Aroclor 1254 and TCDD, and demonstrate that the inhibitory effects of Aroclor 1254 on osteoblast differentiation by the dioxin-like constituents are over-riding the contribution of non-dioxin-like PCBs.
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| 2. |
- Lilienthal, Hellmuth, et al.
(författare)
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Developmental exposure to purity-controlled polychlorinated biphenyl congeners (PCB74 and PCB95) in rats : Effects on brainstem auditory evoked potentials and catalepsy
- 2015
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Ingår i: Toxicology. - : Elsevier BV. - 0300-483X .- 1879-3185. ; 327, s. 22-31
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Tidskriftsartikel (refereegranskat)abstract
- Whereas the effects of dioxin-like polychlorinated biphenyls (DL-PCBs) are well described, less is known about non-dioxin-like PCBs (NDL-PCBs), including influences on the nervous system and related behavioral effects after developmental exposure. Following the examination of the highly purified NDL congeners PCB52 and PCB180, we report here the results of experiments with PCB74 and PCB95. Rat dams were orally exposed to equimolar doses of either congener (40 mu mol/kg bw - 11.68 mg PCB74/kg bw or 13.06 mg PCB95/kg bw) from gestational day (GD) 10 to postnatal day (PND) 7. Control dams were given the vehicle. Adult offspring were tested for cataleptic behavior after induction with haloperidol, a classical neuroleptic drug, and brainstem auditory evoked potentials (BAEPs), using clicks and tone pips of different frequencies for stimulation. Results revealed slight effects on latencies to movement onset in female offspring exposed to PCB74, whereas PCB74 males and offspring exposed to PCB95 were not affected. Pronounced changes were observed in BAEPs at low frequencies in PCB74 offspring, with elevated thresholds in both sexes. PCB95 increased thresholds in males, but not females. Small effects were detected on latency of the late wave IV in both sexes after developmental exposure to PCB74 or PCB95. Compared with the other NDL-PCB congeners tested, PCB74 caused the most pronounced effects on BAEPs. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
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