Biomedical subjects
Publications and source records attributed to Z Vodrázka.
Human serum haemopexine together with albumin participates in the removal of haemoglobin released into the circulation during intravascular haemolysis by a haeme bond and in its transport into parenchymal liver cells.
A new procedure for separation of free and bound ligand in saturation analysis (e.g., radioimmunoassay, competitive protein binding analysis) is presented. The antibody was immobilized on different carriers (glass rods, aluminium or polyethylene strips) covered with a thin layer of polyglycidyl methacrylate. The surface of the polymer had been activated by reaction with either ethylene diamine and glutaraldehyde or sulfuric acid and sodium periodate. The antibody was immobilized on this activated polymer by a covalent bond. The advantages of the presented separation methods are rapidity, simplicity, and conservation of the free and bound ligand equilibrium. A comparison with other separation techniques is carried out.
Proteolytic cleavage of bovine fibrinogen with covalently bound methotrexate (MTX) was studied using four different proteolytic enzymes--trypsin, chymotrypsin, pepsin, and cathepsin D and the interaction of the modified fibrinogen (or fibrin) with HeLa cells was investigated. The presence of fibrin-MTX derivative did not induce any significant morphological alternations of cells. The fibrin-MTX derivative in the gel form was solubilized easily by the action of all proteinases investigated, hydrolysis of highly crosslinked denatured fibrin-MTX in suspension proceeded slower. The solubilized fibrin-MTX degradation products had a strong inhibiting effect on the growth of HeLa cells cultured in monolayer indicating the liberation of chemotherapeutically active MTX from its fibrin derivative.
The binding of folic acid as a model compound and methotrexate as a representative of antifolates to bovine fibrinogen with the aid of 1-ethyl-3-(3-dimethylamino-propyl)-carbodiimide was investigated in order to study the possibility of using fibrinogen as a drug carrier. Soluble modified fibrinogen derivatives containing 0.03-0.1 mg of folic acid or methotrexate per mg of protein were obtained under optimal conditions. These derivatives retained the ability to form fibrin clot by the action of thrombin and to copolymerize with native fibrinogen to the three dimensional fibrin network. At higher concentrations of water soluble carbodiimide, higher temperature and low pH highly cross-linked derivatives of fibrinogen and folic acid (or methotrexate) were formed which were insoluble in water and salt solutions (pseudofibrin). The modified fibrin was extensively proteolytically cleaved by plasmin, pepsin, trypsin and cathepsin D, whereas the proteolysis of insoluble pseudofibrin was very slow.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Chromatography of crude Echis carinatus venom revealed four enzymes with fibrinogenolytic activity and activity to chromogenic substrates, specific for proteases of the coagulation and fibrinogenolytic systems. By employing three-step chromatography on DEAE-Sephacel and Sephacryl S-200, this venom afforded the procoagulation enzyme Ecarin in good recovery (73%) and purification (53-fold). This highly purified preparation has proved to be a single-chain glycoprotein, occurring in two isomers differing in electrical charge and having a low fibrinogenolytic activity.
Explore the source record for details and available documents.
Derivative of bovine fibrinogen (FBG) containing chemically bound methotrexate (MTX) has been prepared by action of ethyldimethylaminopropyl carbodiimide. The derivative retained its solubility and clotability. Intraperitoneally administered FBG-MTX derivative one day after transplantation of the ascitic Gardner lymphosarcoma prolonged distinctly the survival of C3H mice. The intravenous application of FBG-MTX derivative to mice bearing the solid form of the tumor exerted chemotherapeutic effect resulting in prolongation of survival. The local application of FBG-MTX solutions followed by injection of thrombin resulted in the formation of a fibrin clot in the tumor area which persisted at least 48 hours. Local chemotherapy of the solid tumor with fibrin clot containing MTX performed on day 1 or 3 led to significant prolongation of survival of the treated animals. Mechanism of MTX liberation and the possible application of FBG-MTX derivative in chemotherapy of tumors are discussed.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The binding of N-[-5-(6-purinylthio)-valeryl]-glycin ethylester (butocin, PVG) to serum proteins and pure human albumin was studied using the method of equilibrium dialysis. Its binding to protein in sera diluted 1:1 of 10 patients with malignant disease averaged 48.4 +/- 7.07%. At the butocin concentration of 20 micrograms/ml an average of 36% of butocin were bound to pure albumin. Only a small portion was bound to globulin fractions. Measurements of the saturation curve showed butocin to be bound to albumin molecule by one binding centre with a microscopic association constant kappa = 1.7 . 10(3) mol/l.
The interactions of erythrosin with deoxyhemoglobin, oxyhemoglobin, carbonmonoxyhemoglobin, methemoglobin, cyanomethemoglobin and hemoglobin alpha and beta chains have been studied by using the equilibrium dialysis, the difference and circular dichroic (CD) spectra and stopped-flow method. The values of equilibrium and kinetic parameters, as well as CD characteristics, show that in addition to a number of weak binding sites hemoglobin contain four, relatively strong binding sites, one per chain. The properties of the strong binding sites depend on the ligand of the heme group and the charge of the heme group is not directly responsible for this fact. Consequently the properties of deoxyhemoglobin and methemoglobin, differing from the mutually close properties of the other derivatives, confirm that the state of the heme group affects the conformation of hemoglobin molecules in solution. These results are in a good agreement with the classification established on the heme iron spin state.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A new simple filtration technique designed for measuring red cell filtrability in the routine laboratory use was developed. The suspension of the whole blood in saline (1:20,000 dilution) was processed on the Sartorius filter membranes, pore size 8 micron. The percentage of passed erythrocytes indicating red cell filtrability was determined. The suitability and perspective applicability of this method for studying various hematological disorders is proposed.