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  • Springer  (1,297)
  • 1980-1984  (1,295)
  • 1945-1949  (2)
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  • 1
    ISSN: 1432-0827
    Keywords: PTH ; PTH inhibitor ; Cyclic AMP ; Bone resorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of bPTH-(1-84), bPTH-(1-34), [Nle-8, Nle-18, Tyr-34] bPTH-(1-34), bPTH-(1-34) amide (NTA 1-34, desamino bPTH-(1-34), bPTH-(2-34), bPTH-(3-34), and [Nle-8, Nle-18, Tyr-34] bPTH-(3-34) amide (NTA 3-34) were tested in cultured bone cells, isolated from the osteoblast layers of fetal chicken calvaria (cyclic AMP) and in fetal rat calvaria (cyclic AMP, Ca release, and lactate production). Only bPTH-(1-84), bPTH-(1-34), and NTA 1-34 increased cyclic AMP production in a doserelated manner, both in calvaria and in bone cells, whereas all fragments (except NTA 3-34) stimulated bone resorption, the order of decreasing potency being bPTH-(1-84), NTA 1-34, bPTH-(1-34), desamino bPTH-(1-34), bPTH-(2-34), bPTH-(3-34). As in human cells, the antagonist NTA 3-34 inhibited specifically and in a dose-dependent way the cyclic AMP response of maximal concentrations of both bPTH-(1-84) and bPTH-(1-34) in rat calvaria and in chicken bone cells, when measured after short (15 min) and longer (1 1/2–16 h) incubation periods. In addition, measured after 4 h of incubation, NTA 3-34 completely inhibited bPTH-(1-84)-stimulated Ca release using maximal and submaximal concentrations. However, after 6–24 h of incubation, NTA 3-34 had no effect on bPTH-(1-84)-stimulated Ca and lactate release, even at an antagonist/agonist ratio up to 12.5 M, perhaps due to its lower affinity for the PTH receptor. From these findings we propose that (a) in bone there are two types of receptors, one governing demineralization via regulation of the calcium influx and one governing adenylate cyclase activity, and (b) the receptors are different from each other with respect to their affinities toward the agonists and the antagonist.
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  • 2
    ISSN: 1573-5052
    Keywords: Aspect ; Australia ; Direct gradient analysis (DGA) ; Environmental scalar ; Eucalypt ; Generalized Linear Modelling (GLM) ; Radiation index ; Realized niche ; Species response curve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The conceptual framework of direct gradient analysis (DGA) is discussed in relation to the functional, factorial approach to vegetation. Both approaches use abstract simplified environment gradients with which to correlate vegetation response. Environmental scalars based on physical process models of environment and/or known biological growth processes can be incorporated to make analyses less location specific. An example of an environmental scalar (radiation index) for converting aspect and slope measurements to the more biologically relevant radiation input at a site is given. The problem of the shape of species response curves to environmental gradients is examined using a sample of 1 286 plots from eucalypt forest in southern New South Wales. An important conclusion is that skewed or bimodal response curves may be due to unsatisfactory distribution of observations and/or unrecognized environmental factors. The use of Generalized Linear Modelling (GLM) as a method for providing a statistical basis for DGA is presented. Analyses using GLM, and presence/absence data are presented for a range of eucalypt species (Eucalyptus rossii, E. dalrympleana, E. fastigata etc.). Successful prediction of species distributions (realized niches) can be achieved with mean annual temperature, mean annual rainfall, radiation index and geology. Quadratic terms are required in many cases, indicating bell-shaped response curves. The major variability associated with species niches is shown to be related to a limited number (4) of environmental factors. DGA with biologically relevant scalars and appropriate statistical methods is suitable for studying many problems of species' realized niches and plant community composition.
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  • 3
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The usefulness of three simple, commercially available ultrafiltration systems [Centriflo CF25 (A), Centriflo CF50A (B) and Ultrafree (C)] in determining concentrations of unbound carbamazepine in plasma was tested. The concentrations of carbamazepine measured in the first fractions of the ultrafiltrate were low, probably as a result of binding of the drug to the ultrafiltration system. The amount of this binding decreased in the order A 〉 B 〉 C. When using A and B, the first portion of ultrafiltrate obtained after centrifuging for 15 minutes must therefore be discarded. Using the Ultrafree filters this was not necessary. Plasma proteins were found to pass through the Ultrafree filter membrane when more than 0.7 ml ultrafiltrate was collected. Comparison of the ultrafiltration methods with equilibrium dialysis showed a good correlation: r=0.96 (A), r=0.97 (B) and r=0.98 (C). However, in the carbamazepine plasma concentration range 2.5–10.0 μg/ml, significantly lower free fractions were measured with the Centriflo cones. The free fractions measured were: 0.28–0.30 (equilibrium dialysis), 0.17–0.18 (A), 0.22–0.24 (B) and 0.29–0.30 (C). The time required to collect the ultrafiltrate was 30 minutes (A and B) and 2 hours (C).
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  • 4
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of plant pathology 89 (1983), S. 55-66 
    ISSN: 1573-8469
    Keywords: microbial balance ; antagonist ; dynamics of mycoflora ; Alternaria ; Fusarium culmorum ; Gerlachia nivalis ; Microdochium bolleyi ; Mortierella ; Periconia macrospinosa ; Pseudocercosporella herpotrichoides ; Trichoderma ; Typhula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting De schimmelflora van de halmvoet en de wortels werd bepaald in veldproeven, waar benomyl was toegepast in doseringen variërend van 0,24 tot 4,80 kg ha−1. De monsters van de halmvoeten werden drie maal gedurende het groeiseizoen genomen, die van de wortels alleen op het tijdstip van de oogst. Op halmen met diverse symptomen uit onbehandelde proefveldjes kwamenPseudocercosporella herpotrichoides, Gerlachia nivalis enAlternaria-soorten het meest voor, op die uit behandelde domineerdenAlternaria-soorten enFusarium culmorum. Tijdens het afrijpen liepG. nivalis sterk terug en namenAlternaria enF. culmorum toe. Aan het eind van het groeiseizoen verschenenPericonia macrospinosa enTyphula incarnata in behandelde veldjes. De wortelmonsters werden ruim twee maanden na de laatste bespuiting genomen. Resistente schimmels, zoals de porospore Dematiaceae (Alternari, Ulocladium enDendryphion) enMortierella-soorten waren toegenomen in proefveldjes die met 1,20 kg ha−1 of meer waren behandeld. Dat was niet het geval in de veldjes behandeld met de geadviseerde praktijkdosering van 0,24 kg ha−1. Een vermindering van de populatie werd alleen voor zeer gevoelige soorten alsMicrodochium bolleyi enTrichoderma-soorten waargenomen. DeFusarium-soorten, hoofdzakelijkF. culmorum enF. avenaceum, werden niet beïnvloed of bleken te tenderen naar een lichte toename tengevolge van de behandeling. In de discussie is getracht om het zich handhaven van deze betrekkelijk gevoelige schimmels in verband te brengen met een effect van het fungicide op de niet-pathogene schimmelflora.
    Notes: Abstract The mycoflora of culm bases and roots of rye was assessed in field trials, where benomyl was applied at dose rates ranging from 0.24 to 4.80 kg ha−1. Samples of culm bases were taken three times during the growing season, those of roots only at the harvest date. On culms with various symptoms from untreated plots,Pseudocercosporella herpotrichoides, Alternaria spp. andGerlachia nivalis were prevalent and on those from benomyl-treated plotsAlternaria spp. andFusarium culmorum. In later stages of growth,G. nivalis sharply declined andAlternaria spp. andF. culmorum increased. At the end of the season,Periconia macrospinosa andTyphula incarnata appeared in treated plots. In samples of roots taken more than two months after the last spray, porosporous dematiaceous species (Alternaria, Ulocladium andDendryphion), Mortierella spp. and other resistant fungi were prevalent in plots treated with 1.20 kg ha−1 or more, but not in those that received 0.24 kg ha−1, which is recommended for disease control. Lower counts were recorded only for species that are highly sensitive in vitro, e.g.Microdochium bolleyi andTrichoderma spp. Some fusaria were either not affected or tended to be slightly stimulated by the treatment. An attempt was made to attribute the incidence of these moderately sensitive fungi to the effect of the fungicide on non-pathogens.
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  • 6
    ISSN: 1573-904X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 20 (1982), S. 578-584 
    ISSN: 1741-0444
    Keywords: Caries ; Dental enamel ; Impedance ; Permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The permeability of dental enamel membranes can be estimated by means of diffusion-measurements with radio-isotopes. Because of the low intrinsic permeability of these membranes, determination via this route generally takes two weeks. In this paper a much faster electrochemical method is presented, in which the real and imaginary part of the membrane impedance are measured at discrete intervals in the frequency range 10 Hz–300 kHz. From the parameters that describe these electrochemical data, some were found to correlate closely with the permeability of enamel as determined with radio-isotopes on the same enamel sample. From these results it was concluded that especiallyv max, the frequency where the imaginary part of the membrane impedance is maximal, and Z1 at 100 Hz, the imaginary part of the membrane impedance at 100 Hz, are of practical value as predictor for the permeability of enamel.
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  • 8
    Publication Date: 1984-02-01
    Print ISSN: 1385-0237
    Electronic ISSN: 1573-5052
    Topics: Biology
    Published by Springer
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of environmental contamination and toxicology 27 (1981), S. 349-352 
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
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  • 10
    Publication Date: 1981-07-01
    Print ISSN: 0007-4861
    Electronic ISSN: 1432-0800
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Springer
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