[Effect and mechanism of recombinant hirudin on fibrinolysis].

AIM: To study the effect of recombinant hirudin (rH) on tPA-induced fibrinolysis and the possible mechanism of its action. METHODS: The effect of rH on thrombin-fibrin complex (Th-Fn) was detected by 99mTc labeled rH. In the in vitro clot lysis, tPA as plasminogen activator, and recalcified plasma as plasminogen resource were used to study the influence of rH on fibrinolysis by detecting TAFIa, D-Dimer and FXIII. RESULTS: In a canine model of femoral artery thrombosis, a clear radioactivity strip was imaged in 30 - 60 min on a part image, and the femoral vein thrombosis developed at 30 min. rH efficiently inhibited clot regeneration. Addition of TM could inhibit clot lysis obviously, and CPI could shorten the delay of clot lysis which due to TAFIa. There was a dose-dependent relationship with TM concentration and TAFI activation. FXIII activation was inhibited by low concentration of rH ( < or = 0.2 u x mL(-1)), and the level of fibrinolysis product, D-Dimer, increased. CONCLUSION: rH could inhibit the thrombin binding to fibrin. rH inhibited the activation of TAFI and FXIII by combining with thrombin which resulted in enhancement of thrombolysis.

A one-step automated high-radiochemical-yield synthesis of 18F-FECNT from mesylate precursor.

2Beta-carbomethoxy-3beta-(4-chlorophenyl)-8-(2-[(18)F]fluoroethyl)nortropane ((18)F-FECNT) is a potential dopamine transporter imaging agent. In this article, a new mesylate precursor was prepared and a one-step automated synthesis of (18)F-FECNT was developed. The mesylate precursor (4) was synthesized from 2beta-carbomethoxy-3beta-(4-chlorophenyl)tropane (1) by N-demethylation, hydroxyethylation followed by mesylation at a total yield of 47%. [(18)F]fluorination was performed by heating 4mg mesylate precursor and K[(18)F] in 1 ml acetonitrile at 90 degrees C for 20 min. The crude (18)F-FECNT was obtained with a radiolabeling yield of 48%. After purification by preparative high performance liquid chromatography (HPLC), the final (18)F-FECNT product was obtained with a radiochemical purity of 98.4% and a decay corrected radiochemical yield of 33+/-9% (and the uncorrected radiochemical yield was 19+/-5%, n=5). The duration of the total procedure was 80-90 min.

[In vitro inhibitory effect of 23-HBA on angiogenesis].

AIM: To study the inhibitory effect of 23-HBA on angiogenesis in vitro. METHODS: The effect of 23-hydroxy butulinic acid (23-HBA) on the in vitro proliferation of human microcapillary endothelial cells(HMECs) was examined by sulfonylrhodamine B (SRB) assay. The effect of 23-HBA on endothelial cell migration, and tubule formation on Matrigel was also observed. The CD31 expression in HMECs was dectected by immunohistochemical staining. RESULTS: The proliferation of HMECs was inhibited significantly by 23-HBA with IC(50) being 40.44 mg/L. 23-HBA inhibited endothelial cell migration and tubule formation in a dose-dependent manner. The expression of CD31 in HMECs was reduced after treatment with 10 mg/L 23-HBA. CONCLUSION: 23-HBA can inhibit angiogenesis in vitro, which would become a promising antiangiogenic drug.

Quantitative analysis of 23-hydroxybetulinic acid in mouse plasma using electrospray liquid chromatography/mass spectrometry.

23-Hydroxybetulinic acid is a newly isolated derivative of betulinic acid. The agent exhibits potential anti-tumor activity and functions in this regard via apoptosis. In support of pharmacokinetic and toxicological evaluations, a new assay based on liquid chromatography/mass spectrometry (LC/MS) was developed for the quantitative analysis of 23-hydroxybetulinic acid. Sample preparation consisted of extraction of the plasma by the addition of methylene chloride followed by centrifugation. Aliquots of the supernatant were analyzed using an isocratic reversed-phase high-performance liquid chromatography (HPLC) system coupled to a negative ion electrospray mass spectrometer. Molecules of 23-hydroxybetulinic acid and the internal standard limonin were detected using selected ion monitoring at m/z 471 and 469, respectively. The limit of detection of 23-hydroxybetulinic acid was 0.05 pg (0.11 fmol) injected on-column (10 pg/mL, 5 microL injection volume), and the limit of quantitation was 10 pg (21.19 fmol, 2 ng/mL, 5 muL injection volume). 23-Hydroxybetulinic acid was stable in plasma samples at -20 degrees C for at least 3 weeks. The intra-day and inter-day coefficients of variation of the assay were 3.0 and 4.8%, respectively. The utility of the assay was demonstrated by measuring 23-hydroxybetulinicacid in mouse plasma following intragastric administration (IG) in vivo. Pharmacokinetic parameters were calculated using the 3P97 pharmacokinetic software package. A two-compartment, first-order model was selected for pharmacokinetic modeling. The result showed that after IG of 200 mg/kg 23-hydroxybetulinic acid, the plasma concentrations reached peaks at 2 h with C(max) of 3.1 microg/mL. The 200 mg/kg 23-hydroxybetulinic acid suspension IG doses were found to have long elimination half-lives of 25.6 h and low bioavailability of 2.3%. No interference was noted due to endogenous substances. These analytical methods should be of value in future studies related to the development and characterization of 23-hydroxybetulinic acid.