Apolipoprotein (a) attenuates endogenous fibrinolysis in the rabbit jugular vein thrombosis model in vivoBiemond, B.J.; Friederich, P.W.; Koschinsky, M.L.; Levi, M.M.; Sangrar, W.; Xia, J.; Büller, H.R.; ten Cate, J.W. Published in: Circulation Link to publication Citation for published version (APA):Biemond, B. J., Friederich, P. W., Koschinsky, M. L., Levi, M. M., Sangrar, W., Xia, J., ... ten Cate, J. W. (1997). Apolipoprotein (a) attenuates endogenous fibrinolysis in the rabbit jugular vein thrombosis model in vivo. Circulation, 96, 1612Circulation, 96, -1615. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Background In many case-control as well as epidemiological studies, increased lipoprotein(a) [Lp(a)] levels are considered to constitute an independent risk factor for premature coronary artery and cerebrovascular disease. Lp(a) resembles an LDL particle with an additional linked protein [apolipoprotein(a), apo(a)], whose molecular structure has been demonstrated to be homologous to the fibrinolytic proenzyme plasminogen. Because of the high similarity between plasminogen and apo(a), apo(a) may potentially interfere in the fibrinolytic system by competing with plasminogen for fibrin binding sites. In vitro studies have demonstrated that Lp(a) indeed competes with plasminogen binding to fibrin and inhibits tissue plasminogen activator (TPA)-mediated activation of plasminogen. No direct in vivo studies to test this hypothesis have been performed. Methods and ResultsTo test this hypothesis, we studied the effect of a recombinant form of apo(a) on endogenous and TPA-mediated thrombolysis in an in vivo model of experimental venous thrombosis. Thrombi containing either 16 µg r-apo(a), 8 µg r-apo(a), or vehicle (HEPES-buffered saline, control) were formed in the jugular veins of a rabbit and showed significantly reduced endogenous thrombolysis after 60 minutes in a dose-dependent fashion, ID 2.7±0.9% and 4.6±1.8%, respectively, versus 7.4±1.6% of that of the control. High concentrations of incorporated apo(a) significantly reduced TPA-induced thrombolysis (12.2±2.5% versus 22.2±2.6% in the control thrombi), but no effect of lower concentrations of incorporated r-apo(a) was demonstrated on the exogenous TPA-induced thrombolysis.Conclusions The present study dem...

A double-antibody sandwich indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection and quantification of Pythium ultimum. A polyclonal antibody produced to cell walls of P. ultimum was used as the capture antibody, while a P. ultimum-specific mono-clonal antibody (MAb E5) was used for recognition of the fungus. In the ELISA, culture extracts of 7 isolates of P. ultimum exhibited strong positive reactions, whereas none of the 37 isolates of other Pythium spp. and fungal genera had positive reactions. P. ultimum was detected by ELISA in roots of bean, cabbage, and sugar beet seedlings grown in pathogen-infested soil. ELISA optical density readings for infected bean and sugar beet root samples were highly correlated (r > 0.9) with infection levels determined by culturing the samples on water agar. The correlation between the two methods of testing cabbage roots was low, but all cabbage roots in which P. ultimum was detected by culturing were strongly positive in the ELISA. Samples of roots infected with P. irregulare and those with no Pythium infection did not react in the ELISA. The ELISA was highly sensitive; the fungus was detected in culture extracts diluted 1:5,000,000 and in roots with less than 1 infection per 100 cm root.

Background S-Adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are relevant to a variety of diseases. Previous reports that quantified SAM and SAH were based on HPLC or LC–MS/MS. No antibody against SAM has been generated, and the antibody against SAH cannot be used with blood samples. Immunoassays have not been used to measure SAM and SAH. In this study, ELISA was used to measure blood SAM and SAH levels.ResultsSpecific antibodies against SAM were produced for the first time using a stable analog as the antigen. The monoclonal antibodies against SAM and SAH were characterized. No cross-reactivity was detected for the analyzed analogs. For the anti-SAM antibodies, the ELISA sensitivity was ~2 nM, and the affinity was 7.29 × 1010 L/mol. For the anti-SAH antibodies, the sensitivity was ~15 nM, and the affinity was 2.79 × 108 L/mol. Using high-quality antibodies against SAM and SAH, immunoassays for the detection of SAM and SAH levels in blood and tissue samples were developed. Clinical investigations using immunoassays to measure SAM, SAH and the methylation index (MI) in normal and diseased samples indicated that (1) the SAM level is age and gender dependent; (2) the SAM level is associated with the severity of liver diseases, inflammatory reactions and other diseases; and (3) the methylation index (MI) is significantly reduced in many diseases and may serve as a screening biomarker to identify potentially unfavorable health conditions.ConclusionIt is possible to generate antibodies against active small biomolecules with weak immunogenicity, such as SAM and SAH, using traditional hybridoma technology. The antigens and antibodies described here will contribute to the development of immunoassays to measure SAM, SAH and related molecules. These assays enable the MI to be measured specifically, accurately, easily and quickly without costly equipment. This preliminary study indicates that the MI could be an effective indicator of general health, except under conditions that may alter the value of the MI, such as special diets and medications.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-016-2296-8) contains supplementary material, which is available to authorized users.