Search results for "Cattle"
showing 10 items of 608 documents
Photochemical and Photobiological Studies of a Furonaphthopyranone as a Benzo-spaced Psoralen Analog in Cell-free and Cellular DNA
1997
Photobiological activities of the benzo-spaced psoralen analog furonaphthopyranone 3 have been investigated in cell-free and cellular DNA. The molecular geometry parameters of 3 suggest that it should not form interstrand crosslinks with DNA. With cell-free DNA no evidence for crosslinking but also not for monoadduct formation was obtained; rather, the unnatural furocoumarin 3 induces oxidative DNA modifications under near-UVA irradiation. The enzymatic assay of the photosensitized damage in cell-free PM2 DNA revealed the significant formation of lesions sensitive to formamidopyrimidine DNA glycosylase (Fpg protein). In the photooxidation of calf thymus DNA by the furonaphthopyranone 3, 0.2…
Biotin-Labelled and Photoactivatable Aldosterone and Progesterone Derivatives as Ligands for Affinity Chromatography, Fluorescence Immunoassays and P…
1996
New derivatives of progesterone and aldosterone were synthesized and functionally tested with commercially available antibodies. The covalent labelling of antibodies specific for aldosterone and progesterone was detected by SDS/PAGE analysis and subsequent autoradiography after using 3-(O-carboxymethyl)-oximino-(3-[125I]iodo-4-azidosalicylamidobu tylamine) derivatives of aldosterone and progesterone, respectively, as photoactivatable radioligands. Labelling was not observed in the presence of an excess of the unlabelled steroid. Aldosterone was labelled with biotin and used as a tracer in a time-resolved fluorescence immunoassay. The nonradioactive tracer is highly selective for its antibod…
Na+ -dependent neutral amino acid transporters A, ASC, and N of the blood-brain barrier: mechanisms for neutral amino acid removal.
2004
Four Na+-dependent transporters of neutral amino acids (NAA) are known to exist in the abluminal membranes (brain side) of the blood-brain barrier (BBB). This article describes the kinetic characteristics of systems A, ASC, and N that, together with the recently described Na+-dependent system for large NAA (Na+-LNAA), provide a basis for understanding the functional organization of the BBB. The data demonstrate that system A is voltage dependent (3 positive charges accompany each molecule of substrate). Systems ASC and N are not voltage dependent. Each NAA is a putative substrate for at least one system, and several NAA are transported by as many as three. System A transports Pro, Ala, His,…
Activation of the first component of complement, C1: comparison of the effect of sixteen different enzymes on serum C1.
1983
In this study, the effect of sixteen different enzymes on serum C1 and its subcomponents was investigated. The sixteen enzymes could be divided into three groups. First, enzymes which activate native C1: trypsin (optimal concentration 2.4 x 10(-4) mM); alpha-chymotrypsin (2.3 x 10(3) mM); thrombin (1.0 x 10(-5) mM); plasmin (1.9 x 10(-5) mM); elastase (5.8 x 10(-5) mM); pronase (3.0 x 10(-6) mM). All these enzymes are serine esterase and activate native serum C1 bound to EAC4 at the given concentration within 10 min at 30 degrees C. Furthermore, native C1 inhibited by a pentosanpolysulfoester, Sp54, is unable to undergo the internal activation but can be externally activated by the serine e…
Influence of the xyloadenosine analogue of 2?,5?-oligoriboadenylate on poly(A)-specific, 2?,5?-oligoriboadenylate degrading 2?,3?-exoribonuclease and…
1984
The homogeneous poly(A)-specific 2′,3′-exoribonuclease from calf thymus gland, which cleaves both 3′,5′-and 2′,5′-linked oligoriboadenylates, does not degrade (xyloA2'p)2 xyloA, the xylofuranosyladenosine analogue of the 2-5A core. This oligonucleotide, which is supposed to enter intact cells rapidly, was found to possess an increased stability and an enhanced antiherpesvirus activity compared to the natural (A2'p)2A (Eppstein, D. A., Barnett, J. W., Marsh, Y. V., Gosselin, G. and Imbach, J.-L. (1983) Nature 302, 723–724). The poly(A) anabolic enzyme, poly(A) polymerase (Mn2+-dependent), from the same source, which is initiated by (A3'p)2A and its higher oligomers, does not accept 2–5A core…
Covalently Binding of Bovine Serum Albumin to Unsaturated Poly(Globalide-Co-ε-Caprolactone) Nanoparticles by Thiol-Ene Reactions.
2019
When nanoparticles (NPs) are introduced to a biological fluid, different proteins (and other biomolecules) rapidly get adsorbed onto their surface, forming a protein corona capable of giving to the NPs a new "identity" and determine their biological fate. Protein-nanoparticle conjugation can be used in order to promote specific interactions between living systems and nanocarriers. Non-covalent conjugates are less stable and more susceptible to desorption in biological media, which makes the development of engineered nanoparticle surfaces by covalent attachment an interesting topic. In this work, the surface of poly(globalide-co-e-caprolactone) (PGlCL) nanoparticles containing double bonds i…
In situ forming hydrogels of hyaluronic acid and inulin derivatives for cartilage regeneration.
2014
An in situ forming hydrogel obtained by crosslinking of amino functionalized hyaluronic acid derivatives with divinylsulfone functionalized inulin (INU-DV) has been here designed and characterized. In particular two hyaluronic acid derivatives bearing respectively a pendant ethylenediamino (EDA) portion (HA-EDA) and both EDA and octadecyl pendant groups (HA-EDA-C18) were crosslinked through an azo-Michael reaction with INU-DV. Gelation time and consumption of DV portions have been evaluated on hydrogel obtained using HA-EDA and HA-EDA-C18 derivatives with a concentration of 3% w/v and a ratio 80/20 w/w respect to the crosslinker INU-DV. The presence of pendant C18 chains improves mechanical…
Influence of the polymerization step alone on oxygen affinity and cooperativity during production of hyperpolymers from native hemoglobins with cross…
1994
The aim of this study was to find out how the polymerization per se changes oxygen affinity (P50) and cooperativity (n50) of various soluble huge hyperpolymers prepared from native hemoglobins by crosslinking. Increase of cooperativity would be expected considering natural hemoglobin networks. Those hyperpolymers with molecular weights of some 10(6) g/mol are candidates for artificial oxygen-carrying blood additives rather than volume substitutes. Human and bovine hemoglobin reacted with several crosslinkers (2,5-diisothiocyanatobenzenesulfonate (DIBS); 4,4'-diisothiocyanatostilbene-2, 2'-disulfonate (DIDS); 1,3-butadiene diepoxide (BUDE); glutaraldehyde (GDA)) in concentrated (case 1) and …
l-Glutamate receptor binding in bovine retina
1982
Using a centrifugation technique saturable specific [ 3 H]glutamate binding in bovine retina could be demonstrated. Scatchard analysis revealed only one population of binding sites with a dissociation constant of about 3 μ m and a maximal number of binding sites of about 0·2 pmol/mg retinal protein. Several glutamic acid analogues inhibit specific [ 3 H]glutamate binding in bovine retina with half-maximal inhibitory concentrations similar to those reported in other areas of the CNS. Specific [ 3 H]glutamate binding and sodium dependent synaptosomal uptake of glutamate are largely concentrated in the P2 fraction of bovine retina homogenates consisting of conventionally sized synaptosomes. Th…
Pore formation by Vibrio cholerae cytolysin requires cholesterol in both monolayers of the target membrane
2007
Vibrio cholerae cytolysin (VCC) forms oligomeric transmembrane pores in cholesterol-rich membranes. To better understand this process, we used planar bilayer membranes. In symmetric membranes, the rate of the channel formation by VCC has a superlinear dependency on the cholesterol membrane fraction. Thus, more than one cholesterol molecule can facilitate VCC-pore formation. In asymmetric membranes, the rate of pore formation is limited by the leaflet with the lower cholesterol content. Methyl-beta-cyclodextrin, which removes cholesterol from membranes, rapidly inhibits VCC pore formation, even when it is added to the side opposite that of VCC addition. The results suggest that cholesterol i…