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  • Springer  (309)
  • 1
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Trisomy 21 human fibroblasts are more sensitive to human interferon-α (IFN-α) than are diploid controls, consistent with the location of the gene (IFRC) which codes for the IFN-α receptor on chromosome 21. When compared in the antiviral assay, the difference in sensitivity is five-to tenfold, much greater then the 50% difference in IFRC gene dosage. An understanding of the mechanism by which this amplification of gene dosage occurs is relevant to the specific pathology of Down's syndrome and as a model system for studying the pathogenic effects of chromosomal aneuploidy. The enzyme (2′–5′) oligoisoadenylate synthetase (2–5A synthetase), which is believed to be central to the interferon-induced antiviral response, is induced 50% more in trisomy 21 fibroblasts than in diploid controls. Thus the amplification in response occurs subsequent to the binding of IFN-α to its receptor and the triggering of the first set of intracellular events, the latter exemplified by the induction of 2–5A synthetase. Similar results were obtained with IFN-γ, consistent with other evidence which indicates that a gene coding for a separate IFN-γ receptor is also located on chromosome 21.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary When the active sodium-potassium pump (Na−K-ATPase) of shark rectal glands is blocked by ouabain, the concentration of intracellular ions changes in the direction of equilibrium with extracellular fluid. These changes were examined when isolated perfused glands were in the basal state and also when they were stimulated to secrete with cAMP and theophylline, to see whether stimulation affected the passive movement of sodium, potassium and chloride across cell membranes. In basal glands 10−4M ouabain induced an increase of 30 meq/l in intracellular [Na+] and a decrease in intracellular [K+] of about 50 meq/l after 30 min, while intracellular [Cl−] was unchanged. In stimulated glands, these movements were exaggerated. The increase in intracellular [Na+] averaged 112 meq/l, and the decrease in intracellular [K+], 96 meq/l (P〈0.01), while mean intracellular [Cl−] rose by 80 meq/l. Furosemide, 10−4M, partially reversed the accelerated changes in intracellular electrolytes seen after ouabain was added to stimulated glands. These results are consistent with an action of cAMP upon a ouabaininsensitive cotransport of sodium, potassium and chloride in the rectal gland, analogous to that described in avian erythrocytes.
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  • 3
    ISSN: 1432-1424
    Keywords: shark rectal gland ; ouabain binding ; (Na, K)-ATPase ; cyclic AMP ; slices ; isolated cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In an attempt to examine the mechanisms of activation of (Na, K)-ATPase when epithelial transport is stimulated, the binding of ouabain to rectal gland tissue was measured before and after stimulation with dibutyryl cAMP and theophylline. Stimulation significantly altered the characteristics of ouabain binding to slices ofSqualus acanthias rectal gland and to isolated rectal gland cells, accelerating the rate of binding and increasing the amount of ouabain bound at equilibrium when low concentrations of ouabain (10−9 to 10−7 m) were present in the medium. Scatchard plots of ouabain binding were nonlinear, suggesting at least two classes of binding sites, one of higher and one of lower affinity. Stimulation with cAMP and theophylline appeared to increase the affinity of the high-affinity site. Ouabain binding was increased by cAMP and theophylline even in the presence of furosemide (10−4 m) or bumetanide (10−5 m), and when Li+ was substituted for Na+, or NO 3 − for Cl−-maneuvers known to inhibit rectal gland secretion. The changes in ouabain binding induced by cAMP and theophylline do not appear, therefore, to be secondary to secretory activity but may reflect a change in the configuration, environment or location of existing enzyme so as to enhance its activity. Stimulation of ouabain binding cannot be demonstrated in whole homogenates of rectal gland, indicating that intact cells are necessary for the cyclic AMP-induced increase in ouabain binding to become manifest.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1741-0444
    Keywords: Autozeroing ; Barometric method ; Electronic circuit ; Instrumentation ; Plethysmography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract An electronic circuit is described which automatically rezeroes a physiologic signal whenever it reaches the limit of a display. This modified signal can be used for polygraph monitoring while the raw signal is processed by a wide-range high-resolution a.d. convertor. The device is currently used in conjunction with the barometric method for measuring tidal volume, but should find general use in plethysmography.
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  • 5
    ISSN: 1573-2614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Medicine
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 31 (1973), S. 317-325 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The concavity of two functions of a positive matrixA, Tr exp(B + logA) and TrA r KA p K* (whereB=B* andK are fixed matrices), recently proved by Lieb, can also be obtained by using the theory of Herglotz functions.
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  • 7
    ISSN: 1432-0975
    Keywords: Key words Coral Breakage ; Conservation ; Marine Protected Area ; Partial Mortality ; Reef Management ; Stylophora pistillata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  A small-scale, “no-use zone policy” has been implemented since 1992 at Eilat’s Coral Nature Reserve (Northern Red Sea). Six years later, the status of this closed-to-the-public reef area was compared to two nearby open-to-the-public sites, by evaluating populations of the scleractinian coral Stylophora pistillata in the strolling zone (0.5–1.5 m depth). Results from the open sites show that: (1) Live coral cover was three times lower than at the closed site; (2) numbers of small colonies (recruits) were significantly higher than in the closed site, while numbers of medium and large size colonies (geometric mean radius, r¯〉4.1 cm) per m2 were significantly lower; (3) maximum r¯ was almost half than that in the closed site (9.6 cm versus 16.7 cm); (4) average number of broken colonies was three times higher than in the closed site; (5) significantly fewer colonies were partially dead. The latter result may reflect senescence processes in the large colonies of the closed site. Although colony breakage is reduced, it appears that the “no-use zone” policy is not sufficient for protecting small reef areas. The intense exploitation of Eilat’s coral reef by the tourist industry requires’ in addition to the conventional protective measures, the initiation of novel management solutions such as reef restoration by sexual and asexual recruits.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1009
    Keywords: Resident fish ; Hydropower ; Analysis ; Reservoirs ; Models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The US Army Corps of Engineers, the US Bureau of Reclamation, and the Bonneville Power Administration initiated the Columbia River System Operation Review (SOR) in 1990. The SOR will assist agencies in comparing the benefits and risks to Columbia River uses and natural resources from alternative strategies for using Columbia River water. Focusing on 14 federal dams within the basin, the agencies are attempting to improve on the efficient and coordinated use of the Columbia River system. An initial screening of all potential strategies of reservoir operation was necessary to reduce the number of possibilities to a limited set for detailed analysis. To that end, the Resident Fish Work Group of the SOR developed spreadsheet models capable of assessing the impacts of different management strategies on resident fish at six storage reservoirs. The models include biological, physical, and hydrological relationships important to resident fish specific to each reservoir. Alternatives that kept the reservoirs near full pool and held stable during the growing season resulted in positive benefits to resident fish at all locations modeled. Conversely, alternatives designed to improve anadromous fish survival with increased instream flow generally had a negative impact on the resident fish in the reservoirs modeled. The models developed for resident fish in the screening analysis phase of the SOR were useful in assessing the relative impact to resident fish from a large number of alternatives. The screening analysis demonstrated that future analytical efforts must consider trade-offs among river uses/resource groups, among reservoirs throughout the basin, and among resident fish species within a reservoir.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1009
    Keywords: KEY WORDS: Butterfly communities; Grazing; Inventory; Monitoring; Natural history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Cowey and Rolls have shown that the magnification factor with which the retina is imaged onto the striate cortex is proportional to visual acuity. Schwartz has used this to derive how visual peripheral acuity in the human varies with distance from the fovea, in good agreement with experiment. The same reasoning applied to the map of the lower half of the field of view as imaged onto the striate cortex of the cat indicates that the cat fixating a point up to about 100 cm in front of him sees the foreground portion of the horizontal surface on which he is standing approximately uniformly blurred.
    Type of Medium: Electronic Resource
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