ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Bone resorption  (4)
  • Electrochemical oxidation
  • actinorhizal
  • Springer  (6)
  • Oxford University Press
  • Periodicals Archive Online (PAO)
Collection
Keywords
Publisher
  • Springer  (6)
  • Oxford University Press
  • Periodicals Archive Online (PAO)
Years
  • 1
    Electronic Resource
    Electronic Resource
    Electrochemical oxidation of adsorbed alkenoic acids as a function of chain length at Pt(111) electrodes. Studies by cyclic voltammetry, EELS and Auger spectroscopy (1989)
    Springer
    Catalysis letters 3 (1989), S. 275-297 
    Details
    ISSN: 1572-879X
    Keywords: Electrochemical oxidation ; alkenoic acids on platinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Studies of the electrochemical oxidation of a series of straight-chain terminal alkenoic acids adsorbed at a Pt(111) electrode surface are reported. Compounds adsorbed were: propenoic acid (acrylic acid, PPA); 3-butenoic acid (vinylacetic acid, 3BTA); 4-pentenoic acid (allylacetic acid, 4PTA); 6-heptenoic acid (6HPA); and 10-undecenoic acid (10UDA). Vibrational spectra of adsorbed layers were obtained by use of electron energy-loss spectroscopy (EELS). Molecular packing densities were measured by use of Auger spectroscopy. Electrochemical oxidation of each adsorbed layer was explored by means of cyclic voltammetry in aqueous inert electrolyte (KF/HF). As the analogous aliphatic acids are not chemisorbed at Pt under the same conditions, the alkenoic acids evidently adsorb at Pt(111) predominantly through the C=C double bond. Molecular packing densities indicate that the carboxylic acid moiety is in contact with the Pt surface only in the case of PPA. EELS spectra also indicate that the carboxylate groups (other than in PPA) are present as pendants. The carboxylic acid O-H stretching bands of most of the adsorbed acids are red-shifted and broadened, evidently due to extensive intermolecular hydrogen bonding; the exceptions are PPA, for which the interaction is primarily with the Pt surface, and 3BTA, for which intermolecular interaction between the carboxylic acid pendants is apparently prevented by steric considerations. The surface-attached carboxylic acid moieties react with KOH solution, leading to retention of K+ ions, detected by Auger spectroscopy, and to changes in the vibrational spectra indicative of carboxylate anions; reactivity toward KOH decreases with chain length. Adsorbed alkenoic acids at Pt(111) surfaces are stable in water and in vacuum. Oxidation of the adsorbed short-chain acids PPA and 3BTA proceeds to completion, forming CO2 as the principal product. Oxidation of the adsorbed long-chain acids converts the C=C moiety to 2CO2, and transforms the remainder of the molecule to an unadsorbed diacid (likely possibilities are malonic acid from 4PTA; glutaric acid from 6HPA; and heptane-1,7-dioic acid from 10UDA).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00766066
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Inhibition of parathyroid hormone-induced fetal rat bone resorption in vitro by nerve growth factor (1978)
    Springer
    Calcified tissue international 26 (1978), S. 203-208 
    Details
    ISSN: 1432-0827
    Keywords: Nerve growth factor ; Bone resorption ; Parathyroid hormone ; Insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of 7S nerve growth factor (NGF) and its isolated α, β, and γ subunits on bone resorption were assessed in a tissue culture system in which the degree of resorption was determined by measuring the release of45Ca from prelabeled fetal rat radii and ulnae. It was found that 7S-NGF, through the activity of its γ, subunit, inhibits parathyroid hormone (PTH)-stimulated but not-unstimulated bone resorption. The following observations suggest that γ-NGF, a trypsin-like molecule, blocks PTH-induced bone resorption by enzymatic degradation of PTH: (a) γ-NGF does not inhibit bone resorption stimulated by the steroid, 1,25-dihydroxycholecalciferol; (b) trypsin is as effective as γ-NGF in inhibiting PTH-stimulated bone resorption; (c) the PTH-inhibitory action of both γ-NGF and trypsin are eliminated by inactivating these enzymes with diisopropyl fluorophosphate; and (d) addition of γ-NGF to the cultures 2 days after the inclusion of PTH does not result in inhibition of bone resorption. Similarly, when the subunit is added to the culture medium before the hormone, there is no inhibition of resorption. The latter observation suggests that the target of γ-NGF is the PTH molecule rather than its membrane receptors. Crystalline bovine insulin inhibits the γ-NGF suppression of PTH-induced bone resorption. This effect, however, is not mimicked by the addition of zinc, which is present in commerical insulin preparations, to the culture medium. Consequently, insulin must inhibit NGF by some mechanism other than the influence of zinc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013259
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A bone resorbing substance from bovine serum albumin (brA) (1978)
    Springer
    Calcified tissue international 25 (1978), S. 233-240 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Bone resorption ; Albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A fraction (brA), which causes resorption of fetal rat bones in vitro, has been concentrated from bovine serum albumin by anion exchange column chromatography on DEAE Sephadex. This active fraction has also been prepared using DEAE Sephadex A-50 by a batch method with a 0.09M NaCl, 0.1M TRIS buffer, pH 8.35. BrA was 10–30 times more potent than the original albumin. The retained material, which constitutes the bulk of the protein and has less activity than the original albumin, elutes with 0.45M NaCl. Similar treatment of serumα,β or γ globulins does not yield brA. Further enhancement of the bone resorbing activity of brA can be obtained with (NH4)2SO4 fractionation or extraction with CH3OH∶CHCl3. Heating at 55° C for 2 h or at 100° C for 10 min does not affect the activity; overnight incubation with protease destroys the bone resorbing effect. The bone resorbing activity is not removed by dialysis and does not correlate with the protease activity of the fraction. The action of brA is inhibited by 3 mM PO4, 1 μg/ml calcitonin or glucagon, 10−7 M dexamethasone or 0.02 μg/ml actinomycin D. The bone resorbing activity of brA is partially inhibited by 10−7–10−5 M indomethacin. PTH did not elicit bone resorption when added to cultures incubated in chemically defined medium supplemented with 0.1 mg/ml brA. However, brA did not inhibit PTH-induced resorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010775
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Rodent peritoneal macrophages as bone resorbing cells (1979)
    Springer
    Calcified tissue international 27 (1979), S. 255-261 
    Details
    ISSN: 1432-0827
    Keywords: Macrophage ; Bone resorption ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Because of the difficulty in obtaining large, relatively pure populations of osteoclasts, most studies of bone resorption are performed on intact animals or in cultures of embryonic bone rudiments. These experimental systems, however, do not permit detailed analysis of the cellular mechanisms of matrix degradation or of the means whereby resorbing cells attach to the bone surface. Mononuclear phagocytes, which are probably ontogenetically related to the osteoclast, will resorb bone matrix in tissue culture. Consequently, we have developed an in vitro system whereby the ability of these cells to bind and resorb skeletal matrix can be precisely and individually measured using radioisotopically labeled, devitalized rat bone particles. We have found that when derived from mice, peritoneal macrophages bind approximately 80% of bone particles within the first 40 min of incubation. Significant (P〈0.025) net matrix degradation, as defined by the percentage of isotope released from bone cultured with macrophages as compared to that released in the absence of cells, occurs within the first 3 h of culture and proceeds rapidly for at least the first 2 days of incubation. By this time 40%–50% of isotope usually has been released into the medium. Resident peritoneal macrophages appear to mobilize matrix as actively as those which are thioglycollate induced. By comparison, lymphocytes elicit little isotope mobilization from bone, and rat peritoneal exudate macrophages are markedly less efficient (P〈0.001) at resorbing rat bone than are macrophages obtained from mice. Isotope release by peritoneal macrophages represents true cell-mediated resorption and not merely nonspecific mineral mobilization as evidenced by the facts that: (a) the magnitudes of release of isotopes representing the inorganic (45CaCl) and organic (3H-proline) phases of bone are the same, (b) daily buffering of the cultures to pH 7.4 has little effect on45Ca release, and (c) cell-matrix contact is required for optimal mobilization of45Ca or3H.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441194
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Endotoxin inhibition of macrophage-mediated bone resorption (1981)
    Springer
    Calcified tissue international 33 (1981), S. 269-275 
    Details
    ISSN: 1432-0827
    Keywords: Endotoxins ; Bone resorption ; Prostaglandins ; Lipopolysaccharides ; Macrophages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The mechanisms by which bacterial endotoxins (ETX) elicit bone loss in septic osteolytic lesions and in organ cultures of bone rudiments have never been clearly established. The possible mechanisms for ETX action include: (a) the stimulation of osteoclast proliferation; (b) the stimulation of synthesis of secondary agents known to elicit bone resorption, e.g., prostaglandins; (c) the stimulation of the resorptive activity of osteoclasts. In the absence of extant methods for isolating and culturing osteoclasts, we have explored the last possibility by evaluating the action of ETX in a bone resorption system consisting of a putative osteoclast precursor, the macrophage, cocultured with isotopically labeled devitalized bone. We have observed the following: 1. ETX from several species of bacteria (Escherichia coli, Shigella flexneri, andS. minnesota) suppress bone resorption (i.e.,45Ca release) mediated by thioglycollate-elicited peritoneal macrophages. This inhibition occurs at ETX concentrations as low as 0.5 µg/ml and is evident within the initial 24 h of incubation. In marked contrast, ETX does not alter the resorptive activity of resident peritoneal macrophages. 2. The suppression of bone resorption by ETX does not depend on the presence of serum complement nor is it a manifestation of reduced cell viability or cell bone-particle binding. Moreover, prolonged pretreatment of elicited cells with ETX does not reduce their subsequent resorptive activity. 3. The suppressive action of ETX is partially reversed by polymyxin B, an observation which implicates the lipid A component of ETX in the inhibitory process. 4. PGE1, PGE2, and indomethacin at concentrations as high as 10−5M do not alter macrophage-mediated resorption; neither does indomethacin modify the action of ETX when the two agents are used concurrently. However, PGE1 and PGE2 can mitigate the suppressive action of ETX. The latter result indicates but does not define a role for prostaglandin in the ETX phenomenon. We suggest the ETX elicits bone loss in vivo by stimulating osteoclast proliferation or prostaglandin synthesis, and not by directly evoking enhanced bone resorption by osteoclasts or other osteolytic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409448
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Identification of indole compounds secreted byFrankia HFPArI3 in defined culture medium (1989)
    Springer
    Plant and soil 118 (1989), S. 205-209 
    Details
    ISSN: 1573-5036
    Keywords: actinorhizal ; Alnus rubra ; auxin ; Frankia ; IAA ; indole-3-acetic acid ; indole-3-ethanol ; nodule secretion ; phytohormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Indole compounds secreted byFrankia sp. HFPArI3 in defined culture medium were identified with gas chromatography-mass spectrometry (GC-MS). WhenFrankia was grown in the presence of13C(ring-labelled)-L-tryptophan,13C-labelled indole-3-acetic acid (IAA), indole-3-ethanol (IEtOH), indole-3-lactic acid (ILA), and indole-3-methanol (IMeOH) were identified. High performance liquid chromatography (HPLC) and GC-MS with selected ion monitoring were used to quantify levels of IAA and IEtOH inFrankia culture medium. IEtOH was present in greater abundance than IAA in every experiment. When no exogenous trp was supplied, no or only low levels of indole compounds were detected. Seedling roots ofAlnus rubra incubated in axenic conditions in the presence of indole-3-ethanol formed more lateral roots than untreated plants, indicating that IEtOH is utilized by the host plant, with physiological effects that modify patterns of root primordium initiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02232808
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...