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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 19 (1980), S. 3585-3590 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 34 (1980), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effects of catechol estrogens on tyrosine hydroxylase activity in hypothalamic and corpus striatal extracts were evaluated. When assayed in the presence of subsaturating concentrations of pterin cofactor, tyrosine hydroxylase activity was depressed by 2-hydroxyestrone, 2-hydroxyestradiol, Lnorepinephrine, or dopamine. However, estrone, 17β-estradiol, 2- methoxyestrone, or 2-methoxyestradiol had no consistent inhibitory effect on tyrosine hydroxylase activity under in vitro conditions. Moreover, a decrease in pterin binding affinity (elevated Km) in the presence of either catecholamines or 2-hydroxyestrogens was found. These findings were suggestive of a competitive interaction between catechols and pterin. Catechol estrogens and catecholamines were shown to inhibit both membrane-bound and soluble forms of tyrosine hydroxylase. The membrane-bound form of tyrosine hydroxylase, however, was found to have a greater binding affinity (lower Kl) for 2hydroxyestradiol and norepinephrine than did the soluble form. The results of the present study are suggestive of a cytoplasmic effect of estrogen that may be mediated by 2-hydroxyestrogen and terminated by O-methylation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Company
    Nature biotechnology 2 (1984), S. 796-799 
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Antibiotic TA adheres avidly to a variety of surfaces. When administered orally or intravenously to animals, the antibiotic concentrates in an active form close to the site of administration. No measurable blood level of the antibiotic is found. Tissues treated with antibiotic TA and then washed ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Branching heads of symbiotic corals were pulse labeled with either 14C-acetate or 14C-bicarbonate for 1.33 h and the distribution and loss of label was then followed for 16d. The patterns of incorporation and washout were similar for both tracers. Non-solvent-extractable radioactivity (1/3 of the total) was divided into a CaCO3 and an organic fraction, both of which exhibited small if any decrease in radioactivity over 16d. In contrast, total solvent extractable (lipid) radioactivity (2/3 of the total) decreased during the washout period with the first half-life for bicarbonate at 2 d, the second at 4 d and the third could not be measured because of the persistence of a constant amount of radioactivity (18% of Day 1 value) from Day 8 to 16. Of the total retained activity, the zooxanthellae fraction contained between 8–18% from Day 1 to 5. The percentage of total animal (host) radioactivity in lipids rose from 35–40% at 0 time after tracer exposure to 70–90% at 60 min. The majority of 14C fixed into lipids was recovered in the fatty acyl moieties and not in the glycerol moiety as had been previously reported a number of times. These studies suggest that photosynthetically fixed carbon is immediately synthesized into lipid, which is translocated to the host. Analyses of the fatty acid compositions of triacylglycerols (TG) and wax esters (WE) of 40 species of coral from a small patch reef were made. In aposymbiotic species the absence of zooxanthellae appeared to be correlated with higher levels of total lipid, lower percentages of saturated fatty acids and lower TG/WE ratios than in species with symbionts.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Corals in an in situ respirometer exposed to suspended peat during the day greatly decreased net oxygen production, probably due to a reduction of intensity and spectral quality of light reaching the symbiotic zooxanthellae. Net production returned to pre-exposure levels after the chambers were cleared; the corals showed no behavioral effects. In contrast, after exposure during the night, corals displayed clearing behavior (such as extreme distension of the coenosarc and trapping of peat particles in thick clumps of mucus) and an increase in respiration rate comparable to the decrease in net production observed during the daytime exposure. The following morning, net production values were significantly lower than pre-exposure production values although ambient light intensity was slightly higher. This decrease in production as well as a 22% reduction of chlorophyll content in the coral tissue indicated loss of zooxanthellae from the stressed corals. Long-term exposure to such a stress could reduce coral growth rates and substantially alter coral reef communities.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1106
    Keywords: Blinks ; Botulinum toxin ; Blepharospasm ; Orbicularis oculi ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The alterations induced in eyelid movement metrics subsequent to unilateral injections of botulinum toxin type A into the orbicularis oculi muscle were studied in chronic alert monkeys using the search coil technique. Botulinum toxin caused rapid paralysis of blinks in the treated eyelid. The amplitude and peak velocity of blinks generated by this eyelid remained at or below 20% of that of the fellow, untreated eyelid for 10–20 days. Blink amplitude gain increased linearly thereafter, attaining control values by 40–60 days after injection. Recovery of blink peak velocity was slower. The adaptive alterations in blink duration that were observed during the acute phase of toxin paralysis suggest that the mechanisms responsible for blink reflex plasticity may produce bilateral adjustments in eyelid function. Taken together, these data establish a quantitative data base that can be exploited in order to: (1) better understand the neural adaptive mechanisms that operate during eyelid movements and (2) allow quantitative comparisons between current treatment protocols that employ botulinum toxin and protocols that may lead to improvements in the treatment of chronic eyelid spasm (blepharospasm).
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 75 (1983), S. 113-116 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of inorganic carbon concentrations on photosynthetic oxygen evolution of isolated zooxanthellae and coral tips from the hermatypic coral Seriatopora hystrix were measured in the laboratory using an oxygen electrode. Whole coral colonies of Stylophora pistillata were examined in situ, using a bioassay respirometer. Inorganic carbon concentrations above 2.3 mM, the ambient concentration of reef water, generally did not stimulate photosynthesis. These results indicate that inorganic carbon is not limiting to coral photosynthesis and that respiratory carbon dioxide production by the coral host probably has little effect on the photosynthetic rates of its symbiotic zooxanthellae.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    General relativity and gravitation 16 (1984), S. 691-701 
    ISSN: 1572-9532
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Lyapunov's second method is applied to the spherical radiative Robinson-Trautman vacuum space-times to prove that they asymptotically settle down to Schwarzschild space-time. This class of Robinson-Trautman metrics is characterized by the surfaceS being topologically a two-sphere, whereS is invariantly defined by the intersection of the hypersurfacesu=const andr=const. It is shown that ∝ S K 2 dσ is a Lyapunov functional, whereK is the Gaussian curvature anddσ is the invariant measure onS. The critical point occurs atK=0 or, equivalently, at ð2 K=0, which condition is shown to characterize Schwarzschild space-time.
    Type of Medium: Electronic Resource
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