Evaluating thrombolytic efficacy and thrombus targetability of RGDS-liposomes encapsulating subtilisin FS33 in vivo / 生物医学工程学杂志

A novel fibrinolytic enzyme subtilisin FS33, which exhibits much higher activity for decomposing fibrin than urokinase, was purified from Douchi, a traditional soybean-fermented food in China. In order to increase bio-utilization and thrombus targetability of subtilisin FS33 labeled by fluorescein isothiocyanate (FITC), the surface modified liposomes encapsulating subtilisin FS33 and FITC with a synthetic peptide Arg-Gly-Asp-Ser (RGDS), being putatively a specific antagonist of fibrinogen receptor on platelet membrane, were prepared and used to evaluate the therapeutic efficacy in a rat model thrombotic carotid artery. The arterial thrombosis was induced by applying two pieces of filter paper (1 x 2 cm) saturated with 10% of ferric chloride (FeCl3). The rats were infused via the jugular vein with either liposomes carrying BSA (control group) or RGDS-liposomes carrying subtilisin FS33 at doses of 2000 and 4000 U/kg. The plasma of the group infused with RGDS-liposomes showed higher antithrombotic and fibrinolytic activity than did the control group within 15-120 min after infusing. The higher the dose was gived, the higher the activity was shown. APTT(activiated partial thromboplastin time), PT (prothrombin time) and TT (thrombin time) were extended remarkably (P < 0.05, P < 0.01), and FDP (fibrinogen degradation products) also increased greatly (P < 0.01), while ELT (euglobulinlysis time) decreased obviously (P < 0.05). FITC content in heart and brain evidently increased (P < 0.05), and results of D-dimer test were all positive. In addition, the venous thrombi in brain and kidney were dissolved totally or partly as observed by patholgical section. All these indicated that subtilisin FS33 enhanced the antithrombotic and fibrinolytic activities in rat, and RGDS-liposomes improved, in a certain degree, the thrombolytic specificity for targeting to thrombus.

Difference Analysis and Optimization Study for Determination of Fructose and Glucose by Near Infrared Spectroscopy / 分析化学

A total of 101 honey samples that originated from 20 different unifloral honey and other multifloral honey samples were collected from China.FT-NIR spectrometer were applied to determinate the content of fructose and glucose of honey with two different modes: transflectance (800-2500 nm, 2 mm optical path length) and transmittance (800-1370 nm, 20 mm optical path length).It was found that the prediction accuracy of fructose and glucose had significant difference with the two modes.In order to analyze the reason of this difference, support vector machine (SVM) was used to analyze the non-linear information, and genetic algorithm (GA) was used to analyze the characteristic wavelengths.The result indicated that the detection difference of fructose and glucose was originated from their different characteristic wavelengths.Through the optimization of detection method, it was found that for the determination of glucose, short wavelength and long optical path length should be used, on the other side, the whole wavelength region and short wavelength, with selecting the characteristic wavelength to avoid the disturb of water can also be used.For the determination of fructose, whole wavelength region and short optical path length should be used.Linear regression methods such as PLSR could obtain good results, and non-linear methods such as SVM did not improve the model performance.

STUDIES ON FIBRINOLYTIC FUNCTION OF SUBTILISIN AND ITS MECHANISM / 营养学报

Objective:To evaluate the effect how Subtilisin FS33 affect thrombotic and fibrinolytic systems in vitro and in vivo. Method:Activity of Subtilisin FS33 was measured by clot liquefaction time(CLT) . On the model of 10% FeCl3 induced thrombi of carotid arteries in rats,various doses of Subtilisin FS33 were injected to the rats,and the fibrinolytic effect was observed. Results:0.5 g of the unheated blood clots gradually dissolved within 45 min,whereas the blood clots heated at 80℃ for 30 min dissolved within 3 h. This indicated that the enzyme was able to degrade blood clots in the absence of endogenous fibrinolytic factors. The experiment in vivo indicated that high dose subtilisn group could significantly prolong CT(coagulation time ) ,PT(prothrombin time) ,TT(thrombin time ) ,APTT(activated partial thromboplastin time) ,reduce ELT(euglobulin lysis time) ,decrease the content of FIB(fibrinogen) ,increase the content of FDP(fibrinogen degradation products) . D-dimer of all experimental groups waspositive. The venous thrombus in lung and kidney was dissolved totally or partly as observed by pathological section. Conclusion:Both thrombolytic effects of Subtilisin FS33 in vitro and in vivo were significant and the mechanisms might be associated with enhancing anticoagulation activity and fibrinolysis.