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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 19 (1972), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —DOPA and 5-hydroxytryptophan (5-HTP) are generally supposed to be decarboxylated in mammalian tissues by a single enzyme, the two activities being present in constant ratio through a variety of purification procedures. It has now been shown that the ratio of activity of the liver enzyme towards the two substrates can be altered by mild treatments, such as might be used in solubilization of brain preparations. DOPA decarboxylase activity was preferentially inactivated by sodium dodecyl sulphate treatment, and 5-HTP decarboxylation by urea.Previous reports that the two substrates show different pH optima but are mutually competitive, have been confirmed. The Km of the enzyme towards 5-HTP was lowest at pH 7.8 (the optimum pH for decarboxylation of this amino acid), but the variation with pH of the Km towards DOPA was unrelated to the pH optimum for decarboxylation. There appeared to be no relation between the probable ionization state of the substrates and the pH dependence of the enzyme. Studies on the binding characteristics of the enzyme for the two products, dopamine and serotonin, did not show any specific saturable binding.It is proposed that the enzyme has a complex active site, with separate affinity sites for the two substrates, adjacent to a single catalytic site.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 25 (1975), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The uptake into brain and the incorporation into brain protein of intraperitoncally administered, labelled amino acids has been studied in myelinating rats during prolonged hyperphenylalaninaemia maintained by administration of p-chlorophenylalanine. Compared with controls, there was a 50% reduction in both uptake and incorporation into protein of leucine and a parallel reduction in the acid-soluble leucine pool. With glycine and lysine no such changes were observed. On the other hand, when each of the three amino acids was injected directly into the brain, the only significant differences observed between controls and hyperphenylalaninaemic animals were again with leucine, which showed an increased incorporation into protein and an increased specific activity in the otherwise reduced acid-soluble pool.It is concluded that hyperphenylalaninaemia reduces the rate of transport of leucine into the brain and hence reduces the brain pool of leucine, but that any effects on protein synthesis are small. The validity of the model, and the implications of the findings, in relation to phenylketonuria, are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 182 (1958), S. 1512-1513 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Marker2 reported that considerable quantities of pregnanediols were present in the urine of pregnant cows, bulls and steers, but Stevenson3 and Hill4 were unable to substantiate these findings. Aparici5 claimed to have measured large quantities of pregnanediol in the urine of pregnant cows but he ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 185 (1960), S. 612-613 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The isolation of 5p-pregnane - 3oc: 20a - diol from the urine of the pregnant ewe was recently reported by Robertson and Coulson1, As a continuation of this work the neutral ketonic fraction of pregnant ewes' urine was investigated. 22-5 1. of urine representing twenty 24-hr, collections from two ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 10 (1976), S. 47-59 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Surgical replacement of the Achilles and patellar tendons using Dacron mesh silicone prostheses was performed in 15 mature beagle dogs. This part of the study includes clinical evaluation, gross inspection at autopsy of regrown tendons, and histological determination of biocompatibility of prosthetic implants.Functional continuity and integrity of prosthetic patellar tendons have been established by evaluating the biologic-prosthetic interface and the mechanical properties of regrown tendon tissue around and through the Dacron silicone replacements. Results of prosthetic Achilles tendons were less satisfactory because of difficulties in suturing to a muscle and its fascia. Although the prosthetic tendon did not regrow through the tube, it provided a structure for regrowth around it. The regrown tendons became nearly ten times the normal crosssectional area after three to four months and decreased to two to three times after 13 months.Histological studies indicate that in the absence of infection, the Dacron mesh silicone tendon was well tolerated for periods up to 13 months. Overall results are encouraging and warrant further investigation although the regenerative capacity of human patellar and Achilles tendons is unknown.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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