(n.) A rare metallic element, of uncertain identification, supposed to exist in certain minerals, as gadolinite and samarskite, with other rare ytterbium earth. Symbol Tr or Tb. Atomic weight 150.
Example Sentences:
(1) Three classes of Tb3+-binding sites have been found: a first class of low-affinity (Kd = 10 microM) corresponds to magnesium binding sites, located near a tryptophan residue of the protein; a second class of much higher affinity (less than 0.1 microM) corresponds to the calcium transport sites, their occupancy by terbium induces the E1 to E2 conformational change of the Ca2+-ATPase; a third class of sites is revealed by following the fluorescence transfer from formycin triphosphate (FTP) to terbium, evidencing that terbium ions can also bind into the nucleotide binding site at the same time as FTP.
(2) The interaction of three second-generation anthracycline derivatives with polynucleotides, supercoiled DNA, and calf thymus nucleosomes has been studied by terbium fluorescence measurements and agarose gel electrophoresis.
(3) On treatment of the axon with certain agents that include tetrodotoxin, high calcium and terbium, the rebound disappears and the fast phase slows down, increases in size, and has a new slow component added to it.
(4) We have taken continuous thin serial sections through patches of terbium trapped between pericytes and the endothelial cells of continuous capillaries in the rete mirabile of the eel.
(5) Two terbium ions, at least, bind to the Ca2+-ATPase in the close vicinity of FTP when this nucleotide is bound to the ATPase nucleotide site.
(6) The soluble analogue, N-trifluoroacetyladriamycin-14-O-hemiadipate, did show marked effects on terbium fluorescence with all nucleic acids and nucleosomes, but the effects were generally not as striking as were those observed with the epimer, 4'-epi-Adriamycin, which tended to produce a similar effect to its parent drug, Adriamycin, showing that a marked change in the hexose ring did not appreciably affect the interaction of the drug with DNA.
(7) It was concluded that tryptophan in loop position 7 gave optimal luminescence enhancement, and that the additional inclusion of a tyrosine in the loop at positions 2 or 4 could further boost emission from the bound terbium.
(8) Terbium ions and terbium formycin triphosphate have been used to investigate the interactions between the cation and nucleotide binding sites of the sarcoplasmic reticulum Ca2+-ATPase.
(9) We report here on the effects of S-100b on cardiolipin vesicles as investigated by turbidity, terbium-dipicolinate fluorescence and freeze-fracture.
(10) The suitability of the intense Kalpha x rays of terbium emitted in the electron-capture decay of 159Dy for use in transmission imaging and bone mineral analysis is investigated.
(11) Resonance energy transfer from tryptophan residues to terbium occurred only with site A.
(12) The fluorescence excitation and emission spectra of the RNA-terbium(III) complex is reported.
(13) In order to assess their physiological effects, we have examined the action of free terbium ions on the membrane potential and light-evoked responses of horizontal cells, and on the massed light evoked response (ERG) of the neural retina.
(14) Spectroscopically active terbium ions have been used to probe the Ca2+ ion-binding sites on human plasma gelsolin.
(15) The terbium chelate was found to bind tightly (Ka approximately 10(5) M-1) to the protein with a stoichiometry of 1 chelate molecule per protein dimer.
(16) Terbium (Tb3+) competitively inhibited 45Ca2+ binding to fibrinogen during equilibrium dialysis, accelerated fibrin polymerization, and limited fibrinogen fragment D digestion by plasmin.
(17) Calcium concentration dependence shows that this effect is associated with the replacement of terbium by calcium in the transport sites, inducing the E2----E1 transconformation when calcium is bound.
(18) For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay.
(19) We describe an ultrasensitive, enzymatically amplified time-resolved fluorescence immunoassay of thyrotropin (thyroid-stimulating hormone) in serum with use of a terbium chelate as the detectable moiety.
(20) While the rates of activation of calpain I by terbium and calcium are comparable, the rate of activation of calpain II was much greater in the presence of terbium than in the presence of calcium.
Ytterbium
Definition:
(n.) A rare element of the boron group, sometimes associated with yttrium or other related elements, as in euxenite and gadolinite. Symbol Yb; provisional atomic weight 173.2. Cf. Yttrium.
Example Sentences:
(1) The displacement of calcium by ytterbium at the EF site has caused a movement in the polypeptide backbone of Ser-91 and Asp-92.
(2) The elements added to increase radiopacity in the composite materials are barium, strontium, zinc, zirconium, and ytterbium.
(3) Ytterbium attached to sorghum was used as a particulate marker.
(4) The RIHSA or Ytterbium isotope-examination are not an extra burden to the patient if the radiopharmacon is introduced into the dural sac following Queckenstedt's test.
(5) Synthetic triclinic calcium pyrophosphate dihydrate crystals were uniformly trace-labeled with Ytterbium-169 (169Yb), a pure gamma-emitting isotope with a halflife of 31 days.
(6) Use is made of some new ideas that allow quantification of the likely dose homogeneity that can be obtained in a brachytherapy distribution, and in this context ytterbium 169 is shown to be superior to some currently available brachytherapy nuclides.
(7) Nutrient markers were oxides of samarium, scandium, ytterbium, and europium.
(8) Ruminal turnover rates of liquid were measured with chromium-ethylenediaminetetraacetate and solid turnover rates with ytterbium-marked fecal fiber, both dosed through the ruminal cannula.
(9) The addition of ytterbium to calcium-saturated porcine intestinal calcium-binding protein resulted in the appearance of broad lanthanide-shifted resonances well outside the normally observed region of the 1H nuclear magnetic resonance spectrum of the calcium form of the protein.
(10) Samples of duodenal digesta representative of a 24 h period were obtained using chromium-EDTA and ytterbium acetate for flow estimation and 35S as a marker of microbial N entering the small intestine.
(11) Similar results were obtained with ytterbium and tungsten in lumbar spine studies.
(12) In the present study ovarian blood flow was determined before and after a single intravenous injection of LH to anaesthetized, post-pubertal virgin rabbits, using 15 plus or minus 5 mum microspheres, labelled with Ytterbium-169 and Scandium-46.
(13) Isotope studies after injection of Ytterbium 169DTPA into the underlying cyst have shown abnormal patterns in CSF circulation and absorption.
(14) The crystal structure confirms the NMR studies, which suggest that low concentrations of ytterbium cause an extensive displacement of calcium from the EF metal binding site.
(15) Effects of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) derivatives on penetration of ytterbium-169 and cerium-144 into the rat offspring.
(16) Injection of ytterbium-169 as a complex with EDTA or DTPA or injection of Na2Ca EDTA or Na3Ca DTPA 1h after administration of cerium-144 to mothers reduced penetration of both radionuclides into offsprings in relation to the animals receiving no complex compounds.
(17) Ytterbium 169 (half-life 32 days; mean gamma emission 93 keV, after excluding photons of energy less than 10 keV) is a radionuclide with interesting potential for brachytherapy applications.
(18) Penetration of radioactive ytterbium-169 and cerium-144 into fetuses was determined at the end of pregnancy and penetration into the organism of suckling rats was studied during feeding with the milk of exposed mothers when EDTA or DTPA derivatives were being administered.
(19) CT scans of increasing concentrations of ytterbium and iodine showed that at 125 kVp, ytterbium was denser than an equal concentration of iodine.
(20) Of this, 8.8% of the ytterbium had migrated to the hay, 2% was recovered in the supernatant and 89.2% remained bound to the corn.