Role of prophylactic filter placement in the endovascular treatment of symptomatic thrombosis in the central veins.

OBJECTIVES: To evaluate the role of filter implantation in reducing the incidence of fatal pulmonary embolism during the endovascular treatment of thrombosis in the major tributary of the superior vena cava (SVC). METHODS: From October 2004 to October 2008, we conducted a cohort study of 40 patients with thrombosis of the central veins who were preparing for endovascular interventions and received or did not receive filter. The symptom scores were measured, the incidence of pulmonary embolism (PE) was observed, and patient follow-up studies were conducted for three years. RESULTS: One week after therapy, the symptom score improved in both groups compared with before therapy (P <0.001), but no significant difference was found between the scores of the two groups (P >0.05). Four patients in the control group died from PEs after therapy, but no patients in the filter group presented evidence of PE. The survival rates at 1, 2, and 3 years (72.9%, 50%, and 27.1%, respectively) for the filter group were higher than those for the control group (47.6%, 19.0% and 14.3%, respectively; P =0.015). The survival time of patients in the filter group with bronchogenic carcinoma (18 ± 2 months) was longer than that of the patients in the control group (12 ± 2 months) after the endovascular treatment (P <0.001). CONCLUSIONS: Prophylactic filter placement could be a safe and effective method for preventing PE in pre- or post-endovascular-treated patients with thrombi in their central veins.

Heavy metal accumulation by periphyton is related to eutrophication in the Hai River Basin, Northern China.

The Hai River Basin (HRB) is one of the most polluted river basins in China. The basin suffers from various types of pollutants including heavy metals and nutrients due to a high population density and rapid economic development in this area. We assessed the relationship between heavy metal accumulation by periphyton playing an important role in fluvial food webs and eutrophication in the HRB. The concentrations of the unicellular diatoms (type A), filamentous algae with diatoms (type B), and filamentous algae (type C) varied along the river, with type A dominating upstream, and types B then C increasing in concentration further downstream, and this was consistent with changes in the trophic status of the river. The mean heavy metal concentrations in the type A, B and C organisms were Cr: 18, 18 and 24 mg/kg, respectively, Ni: 9.2, 10 and 12 mg/kg, respectively, Cu: 8.4, 19 and 29 mg/kg, respectively, and Pb: 11, 9.8 and 7.1 mg/kg respectively. The bioconcentration factors showed that the abilities of the organisms to accumulate Cr, Ni and Pb decreased in the order type A, type B, then type C, but their abilities to accumulate Cu increased in that order. The Ni concentration was a good predictor of Cr, Cu and Pb accumulation by all three periphyton types. Our study shows that heavy metal accumulation by periphyton is associated with eutrophication in the rivers in the HRB.

Heavy metal contamination of overlying waters and bed sediments of Haihe Basin in China.

The Haihe Basin is in an area of high population density and rapid economic development, and is one of the most polluted river basins in China. Examination of heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) in overlying waters and surface sediments in rivers was conducted in the basin's seven watersheds. Cd concentrations of overlying river waters exceeded Chinese environmental quality standard values for surface water (>0.010 mg/L) at 90% of stations. In surface river sediments, average concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in the basin were 0.364, 13.4, 81.9, 53.3, 435, 27.8, 20.0 and 256 mg/kg, respectively. Cd, Zn and Cu were the most anthropogenically enriched elements, as indicated by enrichment factor (EF) values>1.5; EF values were highest for these metals in the Zi Ya He (ZYH) and Zhang Wei He (ZWH) watersheds. Cd in surface river sediments showed a high potential ecological risk (PER) in the ZYH and ZWH watersheds. The comprehensive PER due to all studied metals was high at many stations, especially in the ZYH and ZWH watersheds. The results indicate that heavy metal contamination in the rivers of the Haihe Basin should be considered when developing basin management strategies for protecting the aquatic environment.

[Ecological stoichiometric relationships of periphyton community elemental composition and variations of water quality in the Chaobai River].

Carbon (C), Nitrogen (N) and Phosphorus (P) of water and periphyton were analyzed in the Chaobai River to investigate how anthropogenic river pollution affected the periphyton community and its elemental composition. The results of this study showed that NH4(+) -N and NO(x)(-) -N accounted for 52%, 28% of TN in the Chaobai River, respectively, while 1.6%, 38% of TN in the Baihe River. TP concentration in the former (0.104 mg x L(-1)) was 21 times higher than the latter (0.005 mg x L(-1)). Coefficient of variation (CV) of periphyton C, N and P in the Chaobai River and Baihe River were 0.55, 0.41, 0.62 and 0.24, 0.13, 0.18, respectively. This indicated great variations of periphyton elemental composition in the Bai River than in the Chaobai River. Binary logistic analysis was used to determine factors that affect periphyton distribution. TOC, TN, NO(x)(-) -N, NH4(+) -N, TP, pH, ORP and conductivity were used in this analysis and the result showed that TP was the key factor which can interpret 87.3% of the correct ratio. Periphyton C, N and P had strong correlations and N was the key element of periphyton composition. N: P can track variations of water TN: TP and this periphyton stoichiometric characteristic can be used as indicators of water pollution. TP was the key pollution factor that determined changes of periphyton N: P. This study laid the foundations of investigating variations of the periphyton community and its effect on structure and elemental cycling of higher trophic levels.

Effect of periphyton community structure on heavy metal accumulation in mystery snail (Cipangopaludina chinensis): a case study of the Bai River, China.

The ratio of metal:P stoichiometry was used to identify the accumulation pathways of heavy metals (V, Cr, Co, Ni, Cu, Cd, and Pb) from periphyton to snails Cipangopaludina chinensis Gray (C. chinensis) in the Bai River watershed. The results showed that periphyton communities were mainly composed of two types of algae, filamentous green algae and unicellular diatoms. The proportion of unicellular diatoms in the periphyton community is a key factor that influences metal accumulation in C. chinensis. The V, Cr, Co, Ni, and Cd content of C. chinensis increased steadily as the corresponding metal content of periphyton increased, but Cu and Pb in the snail did not increase in the periphyton. Mechanisms of V, Cr, and Ni accumulation were found to be related to the proportion of diatoms, while Cd and Pb accumulation were dependent on the physiological characteristics of C. chinensis. The accumulation of Cu in C. chinensis was closely related to their grazing behavior. The metal: P stoichiometry revealed that Cr, Ni, and Cd can reduce the potential ecological risks associated with increased P inputs to the ecosystem. V and Co were considered to be relatively safe, regardless of the periphyton P content. Finally, Pb may not be prone to transfer to higher trophic levels, and may pose the lowest ecological risks of the studied heavy metals, but Cu can cause potential ecological risks when eutrophication has occurred.