RESUMO
The distribution and vertical variation of phosphorus forms in sediments along Xiangxi River were analyzed with Hedley classification method, meanwhile the influences of physical and chemical properties of overlying and interstitial water on the release of phosphorus in sediment were discussed. The major findings showed that the pH values in the overlying and interstitial water increased from 4.72 to 8.55, and were slightly acidic in summer, while weak alkaline in other seasons. The redox potential of sediment was in the reduction state overall. The annual variation range of total phosphorus (TP) content in the overlying and interstitial water, and that in the sediment was 0.02-0.48 mg·L-1 and 0.48-1.45 g·kg-1, respectively. The distribution features of TP content in the sediment were the same with those in the interstitial water along the Xiangxi River. It was interesting that the content of TP in the interstitial water in spring and summer was higher than that in autumn and winter, but that in the sediment of Xiangxi River was opposite. The content of different phosphorus (P) forms decreased successively:HCl-P (HCl extracted phosphorus)> Res-P (residual phosphorus)> NaOH-P (NaOH extracted phosphorus)> NaHCO3-P (NaHCO3 extracted phosphorus)> H2O-P (water-soluable phosphorus). The reductive environment of the interface between sediment and overlying water, and pH of water in spring (weak alkaline) and summer (slightly acidic), were conducive to phosphorus release from sediment into overlying water, increasing the eutrophication risk. TP content in the interstitial water was closely related to that in sediment. The PO43--P in 4 sampling areas diffused from the interstitial water into the overlying water with diffusive fluxes in the range of 0.01-0.04 mg·(m2·d)-1. All of these findings indicated that sediments is an important source of nutrient for the overlying water.
RESUMO
OBJECTIVE: To assess the impact of cytochrome P450 (CYP) 2C19*17 allelic variant on platelet aggregation and bleeding risk in Chinese patients with blood stasis syndrome undergoing percutaneous coronary intervention (PCI) and treated with clopidogrel. METHODS: A total of 520 patients with blood stasis syndrome undergoing PCI after pretreatment with 300 mg clopidogrel and aspirin were studied from July 2009 to April 2011 in Fujian Provincial Institute of Cardiovascular Diseases. CYP2C19*17 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Platelet aggregation induced by 5µmol/L of adenosine diphosphate (ADP) was analyzed with platelet-rich plasma and platelet-poor plasma by turbidimetry method before and after 10 d of treatment with clopidogrel. RESULTS: Bleeding events were observed in 5.96% of patients after thrombolysis for myocardial infarction, and the ratio of patients with CYP2C19*17 allele was 7.98%. The bleeding rate in patients carrying CYP2C19*17 allele, heterozygous (wt/*17) and homozygous (*17/*17), was higher than that in patients with wild-type homozygotes (wt/wt) (P<0.01). At baseline, ADP-induced light transmission at maximal aggregation, 5-min aggregation and disaggregation showed no significant difference among patients with the three different CYP2C19*17 genotypes. However, after 10-day administration of clopidogrel, values of ADP-induced platelet aggregation in *17/*17 and wt/*17 carriers were significantly decreased compared with the wild-type homozygotes (P<0.05, P<0.01); the inhibition rate of platelet aggregation was higher in patients carrying *17/*17 and wt/*17 than those only carrying wt/wt, and the same result was found in disaggregation of platelet after 10-day treatment (P<0.05, P<0.01). Patients with wt/*17 and *17/*17 allele of CYP2C19 showed a higher risk of bleeding than those with wild-type allele (P<0.01), and the occurrence of bleeding was highest in patients with CYP2C19*17 homozygotes. CONCLUSION: CYP2C19*17 allele is associated with enhanced response to clopidogrel and an increased risk of bleeding in patients with blood stasis syndrome of coronary artery disease treated by clopidogrel.
