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Clinical and Applied... Apr 2001Heparinomimetic mannopentaose phosphate sulfate (PI-88) (Progen Industries Ltd. Brisbane, Australia), currently developed as an anticoagulant and antiproliferative...
Heparinomimetic mannopentaose phosphate sulfate (PI-88) (Progen Industries Ltd. Brisbane, Australia), currently developed as an anticoagulant and antiproliferative agent, mainly is composed of a pentomannan. However, tetrasaccharide and disaccharide components are also present. The molecular profile and the anticoagulant potency of PI-88 are investigated in this study. Gel permeation chromatography and polyacrylamide gel electrophoresis analyses were carried out to determine the molecular profile and separation of components of PI-88, respectively. Potentiation of antithrombin III (ATIII) and heparin cofactor-II (HC-II) activity were measured using chromogenic substrate assay. In order to determine anticoagulant and antiprotease effects of PI-88, various global anticoagulant tests, such as the prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), Hep-test (Haemachem Inc., St. Louis), ecarin clotting time (ECT), activated clotting time (ACT), and thromboelastography (TEG) were used. Anti-Xa and anti-IIa activities also were measured. The effect of PI-88 on the release of tissue factor pathway inhibitor (TFPI) was performed in nonhuman primates who received PI-88 and in endothelial cell culture systems. The relative susceptibility of PI-88 to heparinase I, protamine sulfate (PS), and platelet factor 4 (PF4) also was evaluated. The high-performance liquid chromatography profiles of PI-88 showed that its average molecular weight is approximately 2300 Da. Separation and gradient electrophoretic patterns of PI-88 showed that it is composed of five different fractions. This agent activates HC-II through inhibiting the thrombin generation but not inhibiting ATIII. Although PI-88 produced a concentration-dependent prolongation of all of the clotting tests, ECT gave the best correlation in the dose-response curve (ECT, r2 = 0.94; TT, r2 = 0.84; APTT, r2 = 0.69). Heparinomimetic mannopentaose phosphate sulfate (PI-88) exhibited marked inhibition of FIIa, but not of FXa. Heparinase I failed to produce significant neutralization of PI-88 in all the assays used, whereas PS and PF4 partially neutralized the effects of this compound. Heparinomimetic mannopentaose phosphate sulfate (PI-88) produced fivefold increase in the TFPI levels at 15 minutes after intravenous (IV) injection to primates. The incubation of PI-88 in endothelial cell culture system also showed a strong effect on TFPI release. These results suggest that PI-88 exhibited strong antithrombotic and anticoagulant activity in addition to its known antiproliferative properties. Because of the molecular characteristics and the dual nature of the pharmacologic action of PI-88, this agent represents an attractive pharmacologic agent for the control of thrombotic and proliferative disorders.
Topics: Anticoagulants; Antineoplastic Agents; Blood Coagulation Tests; Carbohydrate Sequence; Dose-Response Relationship, Drug; Heparin Lyase; Humans; Lipoproteins; Molecular Sequence Data; Molecular Structure; Oligosaccharides; Protease Inhibitors; Thrombin
PubMed: 11292191
DOI: 10.1177/107602960100700210 -
Biochimica Et Biophysica Acta Mar 2001
Review
Topics: Animals; Antineoplastic Agents; Carbohydrate Sequence; Cloning, Molecular; DNA, Complementary; Endopeptidases; Enzyme Precursors; Extracellular Matrix; Gene Expression Regulation, Enzymologic; Glucuronidase; Heparitin Sulfate; Humans; Molecular Sequence Data; Neoplasms; Oligosaccharides
PubMed: 11250066
DOI: 10.1016/s0304-419x(01)00017-8 -
Clinical and Applied... Jan 2001Ecarin clotting time (ECT) is currently developed for the specific monitoring of antithrombin drugs, such as hirudin, argatroban, and hirulog. Aqueous reagent and dry... (Comparative Study)
Comparative Study
Ecarin clotting time (ECT) is currently developed for the specific monitoring of antithrombin drugs, such as hirudin, argatroban, and hirulog. Aqueous reagent and dry chemistry technology have become available for ECT monitoring of antithrombin agents. Currently, many heparinoids and heparinomimetic drugs are being developed. These agents activate heparin cofactor II (HCII) and primarily mediate their effects by inhibiting thrombin. Although the test is specific for antithrombin agents, heparin cofactor II-mediated thrombin inhibitors are capable of prolonging the ECT. In order to study the relative effects of some of these agents, ECT was measured in human plasma supplemented with Pl-88 (a sulfated pentomanose; Progen Industries Limited, Sydney, Australia), aprosulate, pentosan polysulfate, dermatan sulfate, unfractionated heparin (UFH), and recombinant hirudin (r-hirudin). All agents were supplemented to the citrated-pooled plasma prepared from 10 healthy volunteers at a graded dosage of 0 to 100 microg/ml. These techniques gave comparable results for all of the agents used (PI-88, r2 = 0.99; r-hirudin, r2 = 0.98; UFH, r2 = 0.98; dermatan sulfate, r2 = 0.95; aprosulate, r2 = 0.95; pentosan polysulfate, r2 = 0.94). The relative anticoagulant effects of various agents used on ECT varied widely, exhibiting their potency in the following order: r-hirudin = pentosan polysulfate > dermatan sulfate > PI-88 > aprosulate > UFH. The sensitivity of ECT was adjusted by varying the concentration of the ecarin reagent. The results suggest that HCII-mediated inhibition of thrombin can be detected by using ECT reagents.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Anticoagulants; Antineoplastic Agents; Blood Coagulation; Blood Coagulation Tests; Dermatan Sulfate; Disaccharides; Dose-Response Relationship, Drug; Drug Monitoring; Endopeptidases; Enzyme Inhibitors; Fibrinolytic Agents; Heparinoids; Hirudins; Humans; Oligosaccharides; Pentosan Sulfuric Polyester; Sensitivity and Specificity; Thrombin
PubMed: 11190903
DOI: 10.1177/107602960100700109 -
Science (New York, N.Y.) Jul 1999
Topics: Animals; Conservation of Natural Resources; DNA; Denmark; Genetics, Population; International Cooperation; Laboratories; Molecular Biology; Oligosaccharides; Uganda
PubMed: 10428698
DOI: 10.1126/science.285.5424.35 -
Cancer Research Jul 1999Inhibitors of tumor angiogenesis and metastasis are rapidly emerging as important new drug candidates for cancer therapy. To facilitate the identification of such drugs,...
Inhibitors of tumor angiogenesis and metastasis are rapidly emerging as important new drug candidates for cancer therapy. To facilitate the identification of such drugs, we recently developed novel and rapid in vitro assays for human angiogenesis and for the extracellular matrix-degrading enzyme heparanase, which has been implicated in tumor metastasis. In this study, sulfated oligosaccharides, which are structural mimics of heparan sulfate, were investigated as drug candidates because these compounds may interfere with heparan sulfate recognition by many angiogenic growth factors and may inhibit cleavage of heparan sulfate by heparanase. In the preliminary screening studies, it was found that inhibitory activity in both assay systems was critically dependent on chain length and degree of sulfation, highly sulfated linear oligosaccharides of five or more monosaccharides in length being the most active. However, two sulfated oligosaccharides stood out as potential antitumor drugs, phosphomannopentaose sulfate (PI-88) and maltohexaose sulfate, both of these compounds having the important property of simultaneously being potent inhibitors of in vitro angiogenesis and heparanase activity. Due to the ease of manufacture of the starting material, phosphomannopentaose, PI-88 was studied in more detail. PI-88 was shown to inhibit the primary tumor growth of the highly invasive rat mammary adenocarcinoma 13762 MAT by approximately 50%, inhibit metastasis to the draining popliteal lymph node by approximately 40%, and reduce the vascularity of tumors by approximately 30%, all of these effects being highly significant. Acute hematogenous metastasis assays also demonstrated that PI-88 was a potent (>90%) inhibitor of blood-borne metastasis. Thus, by the use of novel in vitro screening procedures, we have identified a promising antitumor agent.
Topics: Animals; Antineoplastic Agents; Carbohydrate Sequence; Drug Screening Assays, Antitumor; Female; Glucuronidase; Glycoside Hydrolases; Humans; Lymphatic Metastasis; Mammary Neoplasms, Experimental; Neoplasm Metastasis; Neoplasm Proteins; Neovascularization, Pathologic; Oligosaccharides; Organ Culture Techniques; Placenta; Rats; Rats, Inbred F344; Sulfur
PubMed: 10416607
DOI: No ID Found