No abstract

Modulation of the blood coagulation fibrinolytic system is an essential function of vascular endothelial cells. Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) are major fibrinolytic regulatory proteins synthesized by vascular endothelial cells; fibrinolytic activity is dependent on the balance between these proteins. Previously, we have reported that cadmium, an initiator of ischemic heart disease, induces PAI-1 expression and suppresses fibrinolytic activity in cultured human vascular endothelial cells. However, the key molecules involved in cadmium-induced PAI-1 induction remain unclear. Herein, we investigated the contribution of Smad2 and Smad3, transcriptional factors involved in PAI-1 induction via transforming growth factor-β, using the human vascular endothelial cell line EA.hy926 cells in culture. Our findings indicated that cadmium induces PAI-1 expression without affecting t-PA expression up to 20 µM, a non-cytotoxic concentration, and PAI-1 induction by cadmium is partly mediated via Smad2 and Smad3. This study provides a possible mechanism underlying cadmiuminduced vascular disorders.

Off-flavor in drinking water can be caused by transformation products (TPs) generated from organic compounds, such as amino acids, present during chlorination. However, the contributions of many of these TPs to overall off-flavor have not been quantified, mainly because the lack of appropriate chemical standards prevents sensory evaluation by means of a conventional flask test. In the present study, we used gas chromatography-mass spectrometry-olfactometry (GC-MS-O) to identify compounds responsible for the off-flavor generated by chlorination of an aqueous solution of the amino acid phenylalanine, and we propose a sensory evaluation procedure for quantification of the contributions of the identified TPs to the overall off-flavor, regardless of the availability of chemical standards of the TPs. GC-MS-O revealed that two TPs, N-chlorophenylacetaldimine and 2-chloro-2-phenylacetaldehyde, for which chemical standards are not commercially available, were the main components responsible for the off-flavor of the chlorinated solution. By using a sensory evaluation procedure involving a combination of GC-MS-O and a conventional flask test, we quantified the contributions of TPs to the overall off-flavor of the chlorinated solution. Approximately 60% of the off-flavor was attributable to free chlorine (13%), 2-chloro-2-phenylacetaldehyde (13%), trichloramine (12%) phenylacetaldehyde (11%) phenylacetonitrile (8%), and N-chlorophenylacetaldimine (2%). Treatment with powdered activated carbon (PAC) removed the off-flavor. Experiments with chlorination of N-labeled phenylalanine suggested that PAC reductively decomposed trichloramine into N gas and adsorbed all of the other identified TPs. Superfine PAC (median diameter, 0.7 μm) removed the off-flavor more rapidly than normal-size PAC (median diameter, 8.0 μm).

No abstract

No abstract