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F Svec

Publications and source records attributed to F Svec.

At least 163 records · Page 9Linked to original sources
PubMed1975

Extent and topography of the acetylation of calcified chicken-bone collagen.

Acetic anhydride in anhydrous acetone-triethylamine reacts with decalcified bone collagen in two ways. It completely acetylates the e-amino groups of lysine and hydroxylysine and causes a progressive change in the protein matrix, such that increasing amounts of degraded peptides become soluble in alkaline phosphate solution. The peptides produced have molecular weights ranging from 100,000 to less than 2,000 daltons. The number of peptides obtained indicates that there are about 10 bonds cleaved per chain. Ball-mill grinding, particle size of the decalcified bone fragments, and age of the chicken do not affect the fraction of collagen that can be solubilized. The appearance of peptides begins at the point where 90% of the e-amino groups are modified. Both the phosphate-soluble and phosphate-insoluble fractions were essentially completely N-acetylated. Calcified bone under the same conditions is rapidly acetylated to only 45% of the total e-amino groups. With further additions of reagent, the degree of modification of the phosphate-insoluble matrix stabilizes at 50 +/- 4%. At the same time, progressively larger amounts of peptides, soluble in alkaline phosphate solution, are produced. The peptides, which approach 100% N-acetylation, have a distribution of molecular weight from 2000 to 75,000 daltons, indicating 10-15 disrupted peptide bonds per chain. The peptides are initially derived from the more accessible regions of the matrix and subsequently are produced from increasingly inaccessible regions. Chromatography of samples of calcified bone collagen, which were acetylated nearly to completion, indicate that the lysyl and hydroxylysyl residues which are most difficult to modify in the calcified bone are located along continuous regions of the collagen chains. Chromatography of partially acetylated samples also show that all regions of the chains are not uniformly accessible to modification, and further, no single region of every alpha chain is exposed to an identical environment.

Acetates↗
PubMed1975

The effect of long-term administration of N-(2-hydroxyethyl)palmitamide on the chemotherapy of RBA rat leukemia.

The effects of N-(2-hydroxyethyl) palmitamide (PEA) a natural and antitoxic substance on the treatment of RBA rat leukemia were studied. Repeated administration of PEA prolonged substantially survival of leukemic animals in the course of the treatment with cis-diamminedichlor-platinum (cis-Pt(II) in combination with cyclophosphamide, vincristine and methotrexate respectively. The most advantageous combination used was the cis-Pt(II) with methotrexate and PEA administration even improved the treatment results. The long-termed PEA treatment depressed first of all undesirable side effects and enabled to use higher therapeutic dosage of chemotherapeutics and improved the final results.

Animals↗
PubMed1975

Viruses harboured in blasts of the rat myelogenous leukemia (RBA-Le), induced by chicken sarcoma virus.

It was shown that the rat myelogenous leukemia RBA-Le harbours three kinds of viruses. 1. Rat leukemogenic virus, which can be recovered from leukemic cells, medium of cultured leukemic cells and the plasma of leukemic rats. About 12% of rats inoculated when newborn with the recovered virus developed leukemia. 2. Chicken sarcoma virus, which seems to have a lowered infectivity or altered host range as the B77(RBI) virus by which this leukemia had been induced. 3. A cytopathic, hemagglutinating virus, very pathogenic for baby rats, which was shown to be closely related, if not identical in biological as well as immunological properties with Kilham rat virus. The RBA-Le leukemic cells were adapted for growth in tissue culture.

Animals↗
PubMedDate not supplied

New formats of polymeric stationary phases for HPLC separations: molded macroporous disks and rods.

A molding process has been used for the preparation of separation media in different shapes such as rods and flat membrane-like disks. The polymerization is carried out using a mixture of monomers, porogenic solvent and free-radical initiator under conditions that afford macroporous materials with through-pores or channels large enough to provide the high flow characteristics required for applications in chromatography. In contrast to classical suspension polymerization, the solubility of monomers in water does not restrict their use. The versatility of the preparation technique is demonstrated in polymerizations involving both hydrophobic and hydrophilic monomers such as styrene, chloromethylstyrene, glycidyl methacrylate, alkyl methacrylates and acrylamide. Techniques have been developed that allow fine control of the porous properties of the polymers. These, in turn, determine the hydrodynamic properties of the separation devices that contain the molded media. Since all the mobile phase must flow through the separation medium, the mass transport within the molded media is accelerated considerably by convection. Therefore, the separations can be performed at much higher flow rates than in packed columns. This is particularly important for separations of large molecules such as proteins for which diffusion is a serious problem that significantly slows down the separation processes. The molded separation media have been used for the separation of biological compounds using gentle chromatographic modes such as hydrophobic interaction, ion-exchange and affinity chromatography during which the biological activity of the separated compounds is completely retained.

Chromatography↗