Statistical comparison of residential soil concentrations of PCDDs, PCDFs, and PCBs from two communities in Michigan

The University of Michigan dioxin exposure study was undertaken to address concerns that the industrial discharge of dioxin-like compounds in the Midland, MI area had resulted in contamination of soils in the Tittabawassee River floodplain and downwind of the incinerator. The study was designed in a rigorously statistical manner comprising soil measurements of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) from 766 residential properties, selected probabilistically, in the Midland area and in Jackson and Calhoun Counties (Michigan) as a background comparison. A statistical comparison determined that the geometric mean toxic equivalent (TEQ) levels in samples from the target populations were statistically significantly above background. In addition, the probabilities of being above the 75th and 95th percentiles of background were also greater. Congener contributions to the TEQ were dominated by 2,3,4,7,8-PeCDF and 2,3,7,8-TCDF in the floodplain and by 2,3,7,8-TCDD in the incinerator plume. However, PCB 126 was the top congener contributing to the background TEQ. On the basis of statistical inference to the total population, it was estimated that about 36% of the properties in the floodplain and incinerator plume have at least one soil sample over the Michigan Department of Environmental Quality's soil direct contact criterion of 90 pg/g TEQ.

Characterization of Thinopyrum distichum chromosomes using double fluorescence in situ hybridization, RFLP analysis of 5S and 26S rRNA, and C-banding of parents and addition lines

Diagnostic markers for eight Thinopyrum distichum addition chromosomes in Triticum turgidum were established using C-banding, in situ hybridization, and restriction fragment length polymorphism analysis. The C-band karyotype conclusively identified individual Th. distichum chromosomes and distinguished them from chromosomes of T. turgidum. Also, TaqI and BamHI restriction fragments containing 5S and 18S-5.8S-26S rRNA sequences were identified as positive markers specific to Th. distichum chromosomes. Simultaneous fluorescence in situ hybridization showed both 5S and 18S-5.8S-26S ribosomal RNA genes to be located on chromosome IV. Thinopyrum distichum chromosome VII carried only a 18S-5.8S-26S rRNA locus and chromosome pair II carried only a 5S rRNA locus. The arrangement of these loci on Th. distichum chromosome IV was different from that on wheat chromosome pair 1B. Two other unidentified Th. distichum chromosome pairs also carried 5S rRNA loci. The homoeologous relationship between Th. distichum chromosomes IV and VII and chromosomes of other members of the Triticeae was discussed by comparing results obtained using these physical and molecular markers.

Effect of the anticoagulant ethylenediamine tetra-acetic acid (EDTA) on the estimation of pharmacokinetic parameters: A case study with tigecycline and ciprofloxacin

Tigecycline and ciprofloxacin were employed as the model compounds to study the effect of the anticoagulant ethylenediamine tetra-acetic acid (EDTA), which is used during plasma sample preparations, on the determination of pharmacokinetic parameters. The pharmacokinetic parameters were determined in rats following intravenous infusion with blood samples collected in serum separators, with either EDTA- or heparin-coated tubes. The blood-to-plasma (B:P) partition ratio and plasma protein binding were determined in vitro in rat or human blood collected in either EDTA- or heparin-coated tubes. Drug concentrations were quantified by liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS) analysis. In tigecycline-treated rats drug concentrations were twofold lower in EDTA plasma, leading to a twofold lower area under plasma concentration-time curve (AUC) and twofold higher plasma clearance values as compared with those obtained from heparin plasma. No differences were noted in the pharmacokinetic parameters obtained from heparin-treated plasma versus serum. The B:P partition ratio and unbound fraction for tigecycline were significantly higher in EDTA-treated blood. When normalized to the B:P partition ratios, the tigecycline blood clearance values were identical between samples collected in EDTA- or heparin-coated tubes. Similar but smaller differences were observed for ciprofloxacin. It was concluded that EDTA might compete with tigecycline and ciprofloxacin for chelating metal ions and thus affect drug partition between blood and plasma compartments, leading to inaccurate measurement of pharmacokinetic parameters in plasma.

432. How do antiphospholipid antibodies contribute to preeclampsia?

Preeclampsia is characterised by elevated maternal blood pressure which is preceded by endothelial activation. The cause of this endothelial cell dysfunction is unclear but it appears to be triggered by a placental factor. One of the risk factors for developing preeclampsia is the presence of antiphospholipid antibodies (aPL) in the maternal blood but exactly how aPL predispose women to developing preeclampsia is unclear. A second feature known to be associated with preeclampsia is excessive shedding and deportation of dead trophoblasts. We have previously shown that shed trophoblasts are phagocytosed by endothelial cells and that phagocytosis of necrotic trophoblasts leads to endothelial cell activation1. In this study we examined the hypothesis that aPL alter the number or nature of trophoblasts shed from the placenta resulting in endothelial cell activation. Using our published model of trophoblast shedding 2 human first trimester placental explants were treated with monoclonal aPL, IIC5 or ID2, or control antibody CD45 for 72 h. Shed trophoblasts then were harvested and counted using a Cellometer AutoT4 automated cell counter. The activity of caspases 3&7 was analysed in all treated shed trophoblasts using a FLICA™ kit. The treated shed trophoblasts also were exposed to the endothelial cell line HMEC-1 for 24 h. The level of ICAM-1 by HMEC-1 was determined by cell-based ELISA. The number of trophoblasts shed from placental explants was increased 2 fold following aPL treatment whereas, treatment with CD45 resulted in only a 1.3 fold increase in shedding. Trophoblasts shed from aPL-treated explants contained less active caspases 3 & 7 compared with control shed trophoblasts. Moreover, phagocytosis of trophoblasts shed from aPL-treated explants induced significantly increased expression of ICAM-1 compared with controls. aPL treatment affected the number and nature of trophoblasts shed from placentae in such a way that phagocytosing endothelium become activated. These findings suggest that aPL treatment may have shifted the type of cell death that shed trophoblasts are undergoing from apoptosis to a more necrotic or aponecrotic mechanism. This type of shedding of trophoblasts in vivo might contribute to the endothelial cell activation which is a hallmark feature of preeclampsia. (1) Chen Q, Stone PR, McCowan LM et al. Phagocytosis of necrotic but not apoptotic trophoblasts induces endothelial cell activation. Hypertension. 2006;47:116–121. (2) Abumaree MH, Stone PR, Chamley LW. An in vitro model of human placental trophoblast deportation/shedding. Mol Hum Reprod. 2006;12:687–694.