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  • 1
    ISSN: 0920-9964
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Fictive locomotion ; Cutaneous reflex pathways ; Flexor digitorum longus muscle ; Motoneurons ; Interneurons ; Reflex modulation ; Spinal cord
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We examined modulation of transmission of short-latency excitation produced by distal hindlimb cutaneous input, as well as fluctuations in motoneuron membrane potential and input resistance, in flexor digitorum longus (FDL) motoneurons during fictive locomotion. Fictive stepping was induced in unaesthetized, decerebrate cats either by repetitive stimulation of the mesencephalic locomotor region (MLR) or by administration of Nialamide and 1 DOPA after low spinal section. In the MLR preparations, brief depolarizing waves occurred in FDL cells during the early flexion phase of fictive stepping, immediately after cessation of activity in extensor muscles. In some FDL cells, plateau-like depolarizations also occurred during the extensor phase. Fictive stepping induced in acutely spinalized cats by administration of l-DOPA was slower and more variable; peak polarization in FDL motoneurons always occurred during the early flexion phase but there was usually no distinct depolarization during extension. In both types of preparation, the initial EPSP components in synaptic potentials (SP-EPSPs) produced by electrical stimulation of the cutaneous division of the superficial peroneal nerve (SP) were maximally facilitated during early flexion, coincident with the peak of background depolarization. This enhancement was manifested by an increase in the amplitude of initial SP-EPSP components or by decreased central latency of the initial EPSP components, or both. In most FDL motoneurons, input resistance decreased systematically during late flexion, coincident with relative membrane hyperpolarization. Correction of SP-EPSP amplitudes for changes in input resistance suggested that SP-EPSP facilitation persisted throughout the flexion phase These findings are discussed with reference to modulation of cutaneous reflexes during locomotion and the possibility that excitatory last-order interneurons in particular cutaneous reflex pathways may distribute excitatory drive from the central pattern generator for locomotion to FDL α-motoneurons
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1106
    Keywords: Cutaneous EPSPs ; Fictive locomotion ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We examined modulation of transmission in short-latency, distal hindlimb cutaneous reflex pathways during fictive locomotion in 19 decerebrate cats. Fictive stepping was produced either by electrical stimulation of the mesencephalic locomotor region (MLR) or by administration of Nialamide and 1-DOPA to acutely spinalized animals. Postsynaptic potentials (PSPs) produced by electrical stimulation of low threshold afferents (〈 2.5 times threshold) in the superficial peroneal (SP), sural, saphenous or medial plantar nerves were recorded intracellularly from various extensor (n = 28) and flexor (n = 24) motoneurons and averaged throughout the step cycle, together with voltage responses to intrasomatic constant current pulses (in order to monitor relative cell input resistance). Each motoneuron studied displayed rhythmic background oscillations in membrane potential and correlated variations in input resistance. The average input resistance of extensor motoneurons was lowest during mid-flexion, when the cells were relatively hyperpolarized and silent. Conversely, average input resistance of flexor motoneurons was highest during mid-flexion, when they were depolarized and active. The amplitude of the minimum-latency excitatory components of PSPs produced by cutaneous nerve stimulation were measured from computer averaged records representing six subdivisions of the fictive step cycle. Oligosynaptic EPSP components were consistently modulated only in the superficial peroneal responses in flexor motoneurons, which exhibited enhanced amplitude during the flexion phase. With the other skin nerves tested (sural, saphenous, and plantar), no consistent patterns of modulation were observed during fictive locomotion. We conclude that transmission through some, but not all, oligosynaptic excitatory cutaneous pathways is enhanced by premotoneuronal mechanisms during the flexion phase of fictive stepping in several cat hindlimb motor nuclei. The present results suggest that the patterns of interaction between the locomotor central pattern generator and excitatory cutaneous reflex pathways depend on the source of afferent input and on the identity of the target motoneuron population.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0509
    Keywords: Key words: Malignant fibrous histiocytoma—IVC, neoplasms—IVC, tumor thrombus—Contrast-enhanced spiral computed tomography—Magnetic resonance imaging.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Primary malignant tumors of the inferior vena cava are infrequent. We report a very rare case of primary malignant fibrous histiocytoma of the inferior vena cava and describe the contrast-enhanced spiral computed tomographic and magnetic resonance imaging findings.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0032-8332
    Keywords: Black lemur ; Sclater's lemur ; Eulemur ; Natural hybrids ; Intergradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study of intermediate forms betweenEulemur macaco macaco andE. m. flavifrons was performed on animals in different areas located to the north, south, and east of the known limits of distribution in Maromandia. A large hybridization zone was defined and morphological and dermatoglyphic comparisons were done on the different animals.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have studied how collagen production is regulated in fibroblasts obtained from normal and phenytoin-induced hyperplastic human gingiva. Collagen production was determined as collagenase digestible radioactivity and degradation was examined by adding labelled procollagen to the cultures and by pulselabelling in the presence of lysosomal inhibitors. Collagen mRNA levels were measured using a [35S]-UTP labelled proα[1] probe. The normal and phenytoininduced fibroblasts did not degrade collagen extracellularly and lysosomal inhibitors did not enhance collagen production in either culture. Collagen production by the cultures correlated with mRNA levels, and in 2 of 3 phenytoin-induced fibroblasts, which produced more collagen than other cells. collagen mRNA levels were higher. We conclude that collagen production in gingival fibroblasts is primarily regulated by the mRNA levels and that overproduction of collagen by cells from phenytoin-induced hyperplastic gingiva results from an increased steady state level of collagen mRNA and not decreased collagen degradation.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 50 (1995), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5380-5385 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper an analytic analysis of the breakdown voltage of an ion-implanted junction is presented. A joined half-Gaussian distribution of the implanted ions is used, since it gives better description of the impurity profiles. The results are based on a closed-form solution of Poisson's equation in the depletion region. Fulop's average ionization coefficient is used to determine the values for the avalanche breakdown voltage as a function of implantation energy, implant dose, and substrate dopant concentration. The maximum electric field at junction breakdown is also calculated and the results are presented. Finally, the applicability and restrictions of the analysis are discussed.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Multiple population studies have shown the presence of a sibling effect on atopic disease. However, it is unclear if the sibling effect is also of importance in subjects who are genetically at high risk for the development of atopy.Objective To study the presence of a sibling effect on markers of atopy (serum total IgE, specific IgE, skin tests) and asthma (bronchial hyper-responsiveness to histamine) in families ascertained through a parent with asthma.Methods First-degree offspring in 200 asthma families were studied (n = 541). Mixed effects regression models were used to account for the dependence of the observations within a family, and to adjust for possible confounding variables.Results Multiple regression analysis showed that having older siblings was inversely related to atopy, defined as ≥ 2, ≥ 3, ≥ 4, or ≥ 5 skin tests (P = 0.07–0.009). In addition, family size (number of siblings) had a significant protective effect on the presence of specific IgE to common aeroallergens (P = 0.03). Exposure to cigarette smoke in the first 3 years of life significantly increased the risk of having specific IgE to common aeroallergens (P = 0.04). No sibling effect was detected for serum total IgE or bronchial hyper-responsiveness to histamine.Conclusions This study shows a protective sibling effect on the presence and severity of atopy but not on bronchial hyper-responsiveness in children who are genetically at risk. The identification of the sibling effect in high-risk families stresses the need to understand the basis of this effect, in order to design future prevention programmes.
    Type of Medium: Electronic Resource
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