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  • 1
    ISSN: 1432-1106
    Keywords: Long-term potentiation (LTP) ; Ventral posterior medial ; Thalamus ; Somatosensory cortex ; Bicuculline ; in vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Extracellular single-unit techniques were employed to record unitary activity simultaneously from the thalamic ventral posterior medial (VPM) nucleus and the ipsilateral primary somatosensory cortex of adult rats. Cross-correlation analysis triggered by the spontaneous firing of thalamocortical relay neurons in VPM and the discharge of layer IV neurons in the corresponding ipsilateral cortical barrel indicated that the paired-units included in this study were strongly correlated in their activity. The baseline responses of highly correlated cortical/thalamic pairs to a 10 ms deflection of a vibrissa on the contralateral side were measured using poststimulus time histograms. After establishing the baseline response, high frequency activity in VPM was induced in one of two ways: i) direct electrical stimulation of thalamic neurons or ii) whisker stimulation in the presence of bicuculline methiodide (BIC) released near the thalamic neurons. Both methods resulted in a conditioning stimulus (CS) paradigm consisting of “bursts” of high-frequency activity (50–100 Hz) with an inter-burst interval of 150 ms (∼7 Hz). Almost immediately following the presentation of the CS, the response of layer IV cortical neurons to vibrissa stimulation increased by 37–62% over baseline values, which was maintained after the effects of BIC had worn off in VPM. This enhancement in the response of the cortical neurons was not accompanied by a concomitant increase in the thalamic responses. Thus, these results strongly suggest that the potentiation first occurred at the thalamocortical synapse.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of virology 144 (1999), S. 397-405 
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary.  The nucleotide sequences of the entire protein coding regions of the thymidine kinase (TK) genes of macropodid herpesvirus type 1 (MaHV-1) and type 2 (MaHV-2) were determined. The coding region of the MaHV-1 TK gene was 984 bp long and was predicted to encode a polypeptide of 327 amino acids. The coding region of the MaHV-2 TK gene was 1020 bp long and encoded a polypeptide of 340 amino acids. Comparisons of their deduced amino acid sequences with those of fifteen other herpesviruses revealed close homology to those of other alphaherpesviruses, particularly to human herpesvirus type 1 (HHV-1) and type 2 (HHV-2).
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 22 (1982), S. 349-353 
    ISSN: 1432-0428
    Keywords: Diabetes ; db/db mouse ; high fibre diet ; diabetic nephropathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Genetically diabetic mice (C57 BLKsJ db/ db) aged 5–6 weeks were given a diet containing 20% by weight of non-nutritive bulk and compared with age matched control diabetic mice on a normal diet (fibre content 4.5%) and non-diabetic mice. The duration of study was 12 weeks. No adverse effects were observed in animals given the high fibre diet. Total food consumption was greater in mice receiving the fibre enriched diet, but their absolute caloric intake was 6% less than control diabetic mice. Both groups exhibited similar rates of growth and development. Water intake in the experimental diabetic mice was reduced and similar to that of normal non-diabetic mice. Fasting blood glucose was significantly decreased in the experimental diabetic mice at 12 weeks. Renal pathological lesions in the control diabetic mice showed glomerular mesangial expansion and deposition of immunoglobulins within the mesangium. The experimental diabetic animals exhibited significantly less renal pathology, including light and immunofluorescent lesions. It is concluded that addition of non-absorbable fibre to the diet of genetically diabetic mice improves glycaemic control and retards the development of diabetic nephropathy.
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  • 4
    ISSN: 1434-601X
    Keywords: 25.50.Jj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mass distributions of fission fragments have been measured for the reaction of19F on197Au as a function of scattering angle. The mean fragment mass is dependent on the scattering angle, the asymmetry increasing with increasing projectile energy.
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  • 5
    ISSN: 1434-601X
    Keywords: 25.70.−z ; 25.70.Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The competition between fusion-fission and deeply inelastic reactions in the Cl + Ni system has been studied by investigating the exit channelQ-value dependence of theZ-distributions of fission-like fragments. TheZ-, kinetic energy- and angular distributions of the fission-like fragments produced in the37Cl +64Ni system atE lab=170, 186 MeV and in the28Si +74Ge system atE lab=176 MeV have been measured by counter telescopes. TheZ-distribution of the37Cl +64Ni system was found to be essentially the same as that of the35Cl +62Ni system at the same bombarding energy. It is shown that this result can not be explained by the statistical fusion fission model but is consistent with a deeply inelastic model. A systematic study of the fission-like phenomenon in this mass region indicates that the maximum angular momenta for fusion reactions as well as the minimum angular momenta for DIC can be reproduced by the Bass model in the sliding limit (f=1.0) while the maximum angular momenta for fully energy-damped deeply inelastic reactions are governed by the strong interaction radius as predicted by the successive critical distance fusion model. The significance of these results are discussed.
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  • 6
    ISSN: 1434-601X
    Keywords: 25.70.Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The energy damped reaction products from37Cl+12C,27Al,48Ti and16O+48Ti were measured over a wide range of angles (typically 18°〈θ lab〈70°), incident energies (160 〈E lab(37Cl)〈200 MeV,E lab(16O)=118 MeV) and charges Z, including two systems (37Cl+37Al and16O+48Ti) which lead to the same compound nucleus64Zn with the same excitation energy and comparable angular momenta. The angular dependences of total kinetic energy (TKE) and dσ/dθ were decomposed into two components (forward peaked and nearly constant at backward angles), and the elemental TKE and cross sections were derived. The backward components of37Cl+27Al and16O+48Ti exhibit very different Z-distributions, indicating that the fragments do not originate from compound nucleus decay. The results can be understood in terms of an energy damping process.
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  • 7
    ISSN: 1434-601X
    Keywords: 25.85.Ge ; 25.70.Jj ; 25.70.Gh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We examine what information can be obtained from fission angular distributions through precise measurements and an analysis in terms of the simple statistical model of Ericson. We report on the systematics of the decoupling angle and present the role of the angular momentum coupling between the entrance and the exit channel. The results indicate that the directional coupling of the angular momentum in the entrance and the exit channel is always strong for heavy-ion induced fission, and the angular momentum coupling plays a decisive role on the angular distribution of fission fragments. The average channel spins of fission fragments 〈If〉 are deduced through the decoupling angles determined experimentally. They agree well with γ-multiplicity measurements.
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  • 8
    ISSN: 1434-601X
    Keywords: 25.70.Jj ; 25.70.Lm ; 25.85.Ge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The binary decay properties of the47V nucleus, produced in the35Cl +12C reaction, have been investigated at the35Cl bombarding energiesE lab = 180 and 200 MeV by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and a characteristic 1/sin(θ cm) angular distribution. The elemental distribution of the fully-damped products is asymmetric, similar to what has previously been observed in the decay of the56Ni nucleus. Comparison with theoretical model predictions suggests the occurrence of a fusion-fission rather than orbiting process. Moreover the calculations performed using the Extended Hauser-Feshbach Method reproduce well the experimental fission yields. A general discussion of orbiting and fusionfission experimental data of light heavy-ion systems is presented in the framework of the calculated number of available open channels for these systems.
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  • 9
    ISSN: 1432-2013
    Keywords: Corticosterone ; Dexamethasone ; Aldosterone ; Adrenalectomized rats ; Cortical collecting tubule ; Na−K-ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mineralo- and glucocorticoids stimulate renal Na−K-ATPase activity if given over a few days, but their immediate effect on the enzyme (i.e. within the time period required to alter electrolyte transport) remains controversial. We evaluated the short-term (3 h) in vivo effect of physiologic and pharmacologic doses of the natural glucocorticoid (corticosterone) and mineralocorticoid (aldosterone), and of a semisynthetic glucocorticoid (dexamethasone) on Na−K-ATPase activity in cortical collecting tubules microdissected from adrenalectomized rats. This nephron segment was chosen because it is a major target site for both classes of corticoids. Neither corticosterone (0.006, 0.6, and 5 mg/100 g body wt, IM), nor dexamethasone (5 mg/100 g body wt, IM) or aldosterone (10 μg and 50 μg, IV) altered significantly Na−K-ATPase activity in the cortical collecting tubule of these animals 3 h after administration. These results confirm our previous observations in the mouse, and suggest that the enhancing effect of corticosteroids on the renal enzyme seen after longer intervals represents a secondary phenomenon, possibly related to augmentation of the sodium load presented to the pump.
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  • 10
    ISSN: 1573-1561
    Keywords: Danaus plexippus ; monarch butterflies ; Lepidoptera ; Danaidae ; Asclepiadaceae ; milkweeds ; Asclepias syriaca ; Asclepias speciosa ; ecological chemistry ; chemical defense ; cardenolides ; aspecioside ; desglucosyrioside ; syriobioside ; overwintering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The majority (85%) of 394 monarch butterflies sampled from overwintering sites in Mexico contain the same epoxy cardenolide glycosides, including most conspicuously a novel polar glycoside with a single genin-sugar bridge (aspecioside), as occur in the milkweedsAsclepias speciosa andA. syriaca. This cardenolide commonality was established by isolating aspecioside and syriobioside from the wings of overwintering monarchs and the two plant species, and comparing Chromatographie and NMR spectrometric characteristics of the isolates. When combined with the migratory pattern of monarchs and the distribution of these two milkweed species, this chemical evidence lends strong support to the hypothesis thatA. syriaca is the major late summer food plant of monarchs in eastern North America. This finding may be of ecological importance, forA. syriaca contributes less cardenolide and cardenolides of lower emetic potency to monarchs than most milkweeds studied to date.
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