RESUMEN
Based on the analysis of the total concentrations of 10 metals in the sediment core and total concentrations and chemical fractions of seven metals in the surface sediments of Qionghai Lake in Xichang City, Sichuan Province, the spatial-temporal characteristics of metal accumulation and pollution over the past century and the potential ecological risk of metals in surface sediments were studied. Before the 1970s, metal concentrations in the sediment core were stable. The total concentrations of Al, Fe, K, and Cr in the sediment core exhibited visible peaks in the 1970s, which were related to the enhanced input of fine-grained topsoil caused by increasing precipitation, lake reclamation, and deforestation. Since the 1990s, the total concentrations of Al, Fe, K, and Cr decreased with the reduced topsoil erosion, whereas the total concentrations of As, Cd, Cu, Pb, and Zn gradually increased or remained stable. The enrichment factor results showed that Cd, Pb, and Zn were the main contaminants, with Cd as the typical contaminant in the sediment core. The Cd contamination started in the 1960s and has remained at a moderate level since the 1990s. In the surface sediments, the total concentrations of Cd were higher in the northwest lake area, and no visible spatial concentration trends of the other metals were displayed. The bioavailable fractions of Cd, Pb, and Zn accounted for 95%, 63%, and 48% of the total metal concentrations on average. Among the bioavailable fractions, Cd was mainly in the acid-soluble fraction, and Pb and Zn were mainly in the reducible and oxidized fractions. The bioavailable fractions of the other metals were less than 27%. The results of total concentrations and bioavailable fractions of metals revealed that Pb and Zn in the surface sediments were slightly or moderately contaminated, and Cd was moderately contaminated on average. Cd contamination was at a severe level in the northwest lake area. The concentrations of anthropogenic Cd, Pb, and Zn in the surface sediments estimated from the total and bioavailable concentrations were comparable (P>0.05), indicating that anthropogenic metals primarily existed in bioavailable fractions in the sediment. Integrating the assessment results from sediment quality guidelines, potential ecological risk index, and chemical forms of metals, Cd in surface sediments may pose a high ecological risk, whereas the other metals has a low ecological risk.
RESUMEN
OBJECTIVE: To investigate the therapeutic effects of insulin-sensitizing drugs, rosiglitazone and metformin, on nonalcoholic fatty liver disease (NAFLD). METHODS: Forty-four male SD rats were randomized into 4 groups: normal control group (n = 8, fed with normal food) and NAFLD rats (n = 36, fed with high-fat food). Eight weeks later 4 rats were randomly selected from the NAFLD group and were killed to undergo pathological examination of the liver. When the establishment of experimental model of NAFLD rats was confirmed the remaining 32 NAFLD rats were subdivided into 4 equal subgroups: NAFLD control group (to be fed continuously with high-fat food), rosiglitazone treatment group (fed with normal food and rosiglitazone 1.5 mg x kg(-1) x d(-1) by gastric perfusion), metformin treatment group (fed with normal food and metformin 150 mg x kg(-1) x d(-1) by gastric perfusion), and dietary treatment group (fed with normal food and normal saline by gastric perfusion). By the end of the 12th week, all rats were killed to isolate the samples of serum to test the levels of total cholesterol (TC), triglyceride (TG), alanine transaminase (ALT), aspartate transaminase (AST), and tumor necrosis factor-alpha (TNF-alpha). Samples of liver tissue were taken to undergo pathology to examine fatty degeneration and inflammatory cell infiltration and detection of the levels of TC and TG. In the liver the weights of body and liver were measured so as to calculate the liver index. RESULTS: (1) The levels of serum TC, TG, ALT, and AST, liver TC and TG, and liver index of the NAFLD control group increased significantly, and the liver histology of the NAFLD control group expressed moderate to severe fatty degeneration. (2) The serum TC levels of the rosiglitazone and metformin groups were 2.49 mmol/L +/- 0.68 mmol/L and 2.49 mmol/L +/- 0.58 mmol/L, both significantly lower than that of the NAFLD control group (4.55 mmol/L +/- 1.58 mmol/L, both P < 0.001). The serum TG levels of the rosiglitazone and metformin groups were 0.61 mmol/L +/- 0.17 mmol/L and 0.63 mmol/L +/- 0.16 mmol/L respectively, both significantly lower than that of the NAFLD control group (0.85 mmol/L +/- 0.15 mmol/L, both P < 0.001). The serum level of ALT of the rosiglitazone and metformin groups were 38.3 U/L +/- 10.6 U/L and 43.3 U/L +/- 27.5 U/L respectively, both significantly lower than that of the NAFLD control group (110.6 U/L +/- 44.2 U/L, P < 0.001 and P < 0.05). The serum levels of AST of the rosiglitazone and metformin groups were 141.7 U/L +/- 14.3 U/L and 174.5 U/L +/- 57.9 U/L, both significantly lower than that of the NAFLD control group (251.8 U/L +/- 91.0 U/L, both P < 0.05). The liver TG levels of the rosiglitazone and metformin groups were 18.9 mg/g +/- 2.7 mg/g and 20.4 mg/g +/- 3.6 mg/g respectively, both significantly lower than that of the NAFLD control group (54.8 mg/g +/- 7.6 mg/g, both P < 0.05). The fatty degeneration grades of liver tissues of the rosiglitazone and metformin groups were grade: 0.8 +/- 0.3 and 1.0 +/- 0.2, both significantly lower than that of the NAFLD control group (grade 2.8 +/- 0.5, both P < 0.05). The hepatic inflammation scores of: the rosiglitazone and metformin groups were 0.8 +/- 0.2 and 1.0 +/- 0.3 respectively, both significantly lower than that of the NAFLD control group (1.8 +/- 0.4, both P < 0.05). The levels of abnormality in serum TC and TG, liver TG, and liver histology of the dietary treatment group were all alleviated in comparison with the NAFLD control group, but were somewhat severer than those of the rosiglitazone and metformin treatment groups. (3) The serum TNF-alpha levels of the rosiglitazone and metformin treatment groups were 124.6 pg/mL +/- 21.0 pg/mL, 154.9 pg/mL +/- 32.5 pg/mL respectively, both significantly lower than that of the NAFLD group (324.2 pg/mL +/- 34.2 pg/mL, P < 0.001 and P < 0.05). The liver TNF-alpha levels of the rosiglitazone and metformin treatment groups were 0.24 +/- 0.14 and 0.30 +/- 0.12 respectively, both significantly lower than that of the NAFLD group (0.85 +/- 0.12, both P < 0.001). The levels of FAS mRNA expression of the rosiglitazone and metformin treatment groups were 0.22 +/- 0.14 and 0.29 +/- 0.16 respectively, both significantly lower than that of the NAFLD group (0.68 +/- 0.23, P < 0.001 and P < 0.005). CONCLUSION: The insulin-sensitizing drugs, rosiglitazone and metformin, are effective in the treatment of NAFLD.
