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Context:Heliopsis longipes(A. Gray) Blake (Asteraceae), a plant native to Mexico, is used in traditional medicine as analgesic and microbicide. The main component in theH. longipesethanolic extract (HLEE) is affinin, as determined by HPLC/UV–visible and NMR measurement. To date, there is no documented evidence on the spermicidal activity of this extract. Objective: The objective of this study was to assessin vitrothe effectiveness of HLEE as spermicide. Materials and methods: The spermicidal activity of HLEE was evaluated by the Sander–Cramer assay. Spermatozoa were incubated for 20 s with HLEE in concentrations ranging from 75 to 2000 µg/mL to determine the minimum effective concentration (MEC) value. The 50% effective concentration (EC50) of HLEE was estimated by assaying serial dilutions from the MEC. Additionally, sperms were incubated with 125, 250, or 500 µg/mL of HLEE to evaluate the viability and the integrity of sperm membrane. Lipid peroxidation was assessed by the thiobarbituric acid reactive substances assay. Results: HLEE caused an inhibition of 100% in spermatozoa motility at a MEC value of 2000 µg/mL; the EC50value was 125 µg/mL. Additionally, exposure to HLEE at 125, 250, or 500 µg/mL for 30 min decreased sperm viability to 27%, 8%, and 2% of the control value, respectively, and significantly increased the percentage of sperms with structurally disorganized membrane. HLEE also increased significantly the level of lipid peroxidation in sperms with respect to controls. Discussion and conclusion: The results demonstrate the spermicidal activity of HLEEin vitroand suggest that this action is caused by oxidative damage and alterations in the spermatozoal membrane. [ABSTRACT FROM PUBLISHER]

Abstract: Recent studies point to dramatic ‘mandate switches’ by elected politicians, while others suggest higher levels of mandate loyalty. Yet, two of the oldest party systems in Latin America, Colombia and Venezuela, have not been extensively examined. Legislative activity across single issue parties is examined to determine whether they are able to stay focused and consistent with the party's policy goals. The analysis identifies the importance of stated policy goals, which are likely to provide long-term electoral benefits, and nomination procedures as important determinants of legislative action among single issue parties. The results shed a new light on parties in Latin America by suggesting that parties are capable of acting in accordance with their stated single-issue platforms. [Copyright &y& Elsevier]