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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc.
    Wound repair and regeneration 12 (2004), S. 0 
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Chronic venous stasis ulcerations (VSU) are associated with significant platelet and leukocyte activation with secondary superoxide anion and ROS production that may severely degrade nitric oxide (NO) production. This study was designed to document the possible association between NO production and the impaired healing of VSU patients. Twenty-four subjects were used for the study. Group C (n = 8) the control group, consisted of healthy adults without history of VSU. Group HU (n = 8) the healed ulcer group, consisted of adults with documented VSU whose ulcers healed with routine wound care and compression therapy in 20 weeks or less. Group UU (n = 8) the unhealed ulcer group, consisted of adults with documented VSU without healing within 20 weeks. All groups had normal renal function and were hospitalized for 24 hours on bed rest with a low arginine and low nitrate diet. Fasting samples were obtained for plasma and urine nitrate (NOx) and plasma arginine, asymmetric dimethylarginine (ADMA) and isoprostane determinations. At 24-hrs, group HU demonstrated the highest plasma NOx levels (33.25 ± 11.69 μM) as compared to group C (19.45 ± 2.63 μM) or group UU (27.17 ± 3.67 μM); urine NOx excretion of group UU (51.46 ± 11.77 μM) was significantly lower (p 〈 0.05; Kruskal-Wallis) as compared to group HU (135 ± 38.29 μM) or group C (164.3 ± 38.58 μM). ADMA and arginine were not significantly different between groups. Ratios of NOx to isoprostane were disproportionate between groups. These results suggest, for the first time, a significant relationship between impaired VSU healing and deficient NO production. Furthermore, these findings establish the clinical value of measurements of NO production and bioavailability as effective predictivebiological markers for the healing of VSU.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0034-5687
    Keywords: Animal, man ; Breath holding ; Breathlessness ; Dyspnea ; Hypercapnia ; Paralysis ; Respiratory muscle, paralysis ; Sensation of respiration ; sensation of
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Animal Behaviour 16 (1968), S. 29-31 
    ISSN: 0003-3472
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 178 (1996), S. 463-475 
    ISSN: 1432-1351
    Keywords: Insect hearing ; Auditory system evolution ; Serial homology ; Ultrasound ; Acoustic behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Unlike most praying mantises that have a single region of auditory sensitivity, species in the genus Creobroter have equally sensitive hearing at 2–4 and at 25–50 kHz and and are relatively insensitivity at 10–15 kHz — they have a W-shaped audiogram. Ultrasonic sensitivity originates from an auditory organ in the ventral midline of the metathorax that closely resembles the ear of other mantises. Ablation experiments demonstrate that low frequency sensitivity derives from a serially homologous mesothoracic auditory organ. Extracellular recordings suggest that these two ears operate largely, if not entirely, independently of one another in the thorax. The low frequency response has a longer latency, more action potentials per stimulus, and different patterns of change with increasing SPL than the high frequency response. Separate interneurons mediate responses in the two frequency ranges, but our evidence suggests that they are two serially homologous sets of cells. Neither auditory organ shows any physiological evidence of directional sensitivity. Ultrasound triggers a set of behaviors in flying hymenopodid mantises much like those in other mantises, but the behavioral significance of low frequency hearing in these animals is still unknown.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 173 (1993), S. 415-424 
    ISSN: 1432-1351
    Keywords: Electroreceptor ; Burst Duration Coder ; Gymnotiform electric fish ; Frequency tuning ; Cascade model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This paper examines the directionality of tuberous electroreceptor responses and relates them to a polarity bias seen for passive electrolocation by electric fish (Hypopomus). We recorded from Burst Duration Coders (BDCs) while stimulating with 1 kHz single period sine waves with electric fields oriented horizontally in different directions. Electroreceptors have figure-8 directional sensitivity profiles with two, usually unequal lobes of sensitivity separated by 180°. For most units the larger lobe points inward, while for a few, the lobes are symmetrical or the larger lobe points outward. The differences correlate with differences in frequency tuning of the receptors. We can alter, and even reverse, the directional asymmetry of a single unit by changing the frequency of the stimulus. Two general response profiles result, with two corresponding classes of tuning curves. The degree of asymmetry varies with position on the body surface. The asymmetries and the effects of stimulus frequency and of tuning can be modeled with a linear/non-linear/linear cascade filter. The behavioral preference for approaching the head end ( + ) of an electrode is difficult to understand in light of the asymmetry of responses we report for amplitude-coding BDCs but can be understood by reference to the time-coding Pulse Marker (PM) receptors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 173 (1993), S. 401-414 
    ISSN: 1432-1351
    Keywords: Electroreption ; Electric fish ; Gymnotiform ; Burst Duration Coder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This paper is an electrophysiological study of the directionality of the tuberous electroreceptors of weakly electric fish. We recorded from two classes of tuberous electroreceptors known for pulse gymnotiforms: Burst Duration Coders (BDCs), and Pulse Markers (PMs). Both code for stimulus amplitude, although the dynamic range for BDCs is greater, and both exhibit strong directional preferences. Polar plots of spike number (for BDCs) or spike threshold (for PMs) versus electric field azimuth, are figure-8 shaped with two asymmetrical, elliptical lobes separated by 180°. The best azimuth of these two types of receptors from a given body region correlate with each other and with measures of best azimuth for transepidermal current flow. The shape and asymmetry of the directionality profiles appear to be caused by filter dynamics of the receptors. Pulse Markers are located on the anterior part of the body surface while Burst Duration Coders are located all over. The best directions of receptors in the anterior third of the body vary systematically with location from 0° to 180°. This region is probably critical for determining the direction of local electric fields. Together these receptors provide the CNS with sufficient information to construct a map of horizontal plane electric field directions.
    Type of Medium: Electronic Resource
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