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  • Artikel: DFG Deutsche Nationallizenzen  (5)
  • Kitten LGN  (3)
  • Cigarette smoke  (2)
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  • Artikel: DFG Deutsche Nationallizenzen  (5)
Materialart
Erscheinungszeitraum
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 31 (1978), S. 193-206 
    ISSN: 1432-1106
    Schlagwort(e): Kitten LGN ; Development ; Visual acuity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The spatial resolving power and receptive field properties of ‘sustained’ cells in layers A and A1 of the lateral geniculate nucleus (LGN), which received inputs from the area centralis of the retina in kittens of 3–16 weeks of age had been studied. The basic concentric organisation of receptive fields of ‘sustained’ LGN cells receiving inputs from the area centralis appeared to be already laid out at 3 weeks in kittens. Spatial resolving power of the cells determined using the highest spatial frequency of a sinusoidal grating resolved by cells as a measure of cellular visual acuity, however, developed gradually to the level of adult LGN cells during the sensitive period (3–12 weeks). Although this development occurred alongside the process of maturation of ocular alignment and the refractive state of the eyes, following the clearing of the embryonic vasculature of the ocular media from the 4th week onward, it depended on the enhancement of distinct inhibitory surround mechanisms taking place during the 6th–11th week. The course of development of spatial resolution of ‘sustained’ LGN cells receiving inputs from the area centralis of the retina runs parallel with the developmental curve of visual acuity in kittens obtained by visually evoked responses or by behavioural techniques by previous workers. The neural mechanisms which subserve high visual acuity are therefore already determined at the LGN before the inputs of the two eyes are mixed at the visual cortex.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-1106
    Schlagwort(e): Kitten LGN ; Convergent squint ; Visual development ; Amblyopia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In twelve kittens, convergent squint was surgically produced at either 3, 6, 8, 10, 13, or 16 weeks. When these kittens reached the age of 4–8 months, the spatial resolution of ‘sustained’ cells which received inputs from the area centralis in layers A and A1 of both the left and right lateral geniculate nucleus (LGN) was measured under nitrous oxide/halothane anaesthesia, using the highest spatial frequency of a sinusoidal grating resolved by cells as a measure of cellular visual acuity. Spatial resolution of cells fed by the squinting eye's area centralis was poorest in the kittens in which the squint was produced at 3 weeks. The resolution of the cells driven by the area centralis of the squinting eye gradually improved for the kittens in which the squint was produced at progressively later stages. There was no effect of convergent squint on the resolving power of cells in the kittens in which squint was produced at 13 weeks and 16 weeks. The developmental curve of spatial resolution of LGN cells obtained from normal kittens of different ages was found to fit very closely with a plot of the spatial resolution of cells driven by the squinting eye against age at squint production. These results suggest that the loss of spatial resolution (amblyopia) in the eye with convergent squint is due to the arrest of development of spatial resolution during the sensitive period in early postnatal life. Clinical implications are discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 25 (1976), S. 63-77 
    ISSN: 1432-1106
    Schlagwort(e): Kitten LGN ; Single cell ; Convergent squint ; Visual acuity ; Amblyopia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The spatial resolution of LGN cells has been studied in 4–5 month old kittens raised with convergent squint surgically produced in one eye at the age of 3–4 weeks. The ‘sustained’ cells which received inputs from the central retina of the squint eye showed significantly poorer spatial resolution (determined by the highest spatial frequency of a sinusoidal grating to which a cell responded with modulated firing) than those which received inputs from the central retina of the normal eye. The spatial resolution of cells which received inputs from the peripheral retina of the squint eye was not different from that of cells receiving inputs from the peripheral retina of the normal eye. The visual latency of ‘sustained’ cells which received an input from the area centralis of the squint eye was considerably lengthened and the response showed a sluggish onset. Thus the most important clinical symptom of amblyopia, namely the reduction of foveal visual acuity, has been demonstrated in kittens raised with unilateral vonvergent squint. The results suggest that the lesion responsible for amblyopia due to squint might be a functional degeneration of the high spatial frequency tuning cells in the pathway prior to the visual cortex, i.e. in the retina or LGN.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-1750
    Schlagwort(e): Guinea pig ; Ozone ; Cigarette smoke ; Airway hyper-responsiveness ; Vascular permeability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of combined exposure to ozone and cigarette smoke on airway responsiveness and tracheal vascular permeability, compared with those of single exposure were examined in guinea pigs. Airway responsiveness was assessed by measuring the specific airway resistance (sRaw) as a function of increasing concentration of inhaled methacholine aerosol immediately, 5 hr, and 24 hr after exposure. In a parallel study, tracheal vascular permeability was quantified by measuring the tracheal extravasation of intravenously administered Evans blue dye. Neither exposure to 1 ppm ozone for 30 min nor 5 puffs of cigarette smoke increased airway responsiveness or vascular permeability at any time after exposure. Combined exposure to 1 ppm ozone for 30 min and 5 puffs of cigarette smoke caused airway hyperresponsiveness and increased vascular permeability immediately after exposure. Exposure to 1 ppm ozone for 90 min increased both airway responsiveness and vascular permeability immediately after exposure. Exposure to 10 puffs of cigarette smoke increased airway responsiveness but not vascular permeability immediately after exposure. Combined exposure to 1 ppm ozone for 90 min and 10 puffs of cigarette smoke increased both airway responsiveness and vascular permeability immediately after exposure. The combined exposure to ozone and cigarette smoke thus increased both airway responsiveness and tracheal vascular permeability to a greater extent than did exposure to a single agent, suggesting that a combination of air pollutants has a more deleterious effect both on airway responsiveness and on tracheal vascular permeability than does either agent alone in guinea pigs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1432-1750
    Schlagwort(e): Guinea pig ; Cigarette smoke ; Airway hyperresponsiveness ; Superoxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To investigate the involvement of superoxide in airway hyperresponsiveness and bronchoconstriction induced by cigarette smoke (CS), we evaluated the effects of superoxide dismutase (SOD), a scavenger of superoxide anion, and apocynin, an inhibitor of superoxide anion-generating NADPH oxidase in phagocytes, on the airway responses induced by CS in conscious guinea pigs. Airway responsiveness was assessed by PC2OOMch, the concentration required to produce a doubling in the baseline specific airway resistance (sRaw) to an inhaled methacholine aerosol, in nonanesthetized spontaneously breathing animals. Before being exposed to ten puffs of CS, animals inhaled either SOD (5,000 units/ml or 25,000 units/ml) or vehicle. Although SOD did not affect PC2OOMch, in the air control group, this agent significantly reduced the CS-induced airway hyperresponsiveness. Repeated administration of apocynin (12 mg/kg for 4 days) did not affect PC2OOMch, after exposure to CS. These data suggest that the superoxide from CS was involved in the airway hyperresponsiveness induced by CS, whereas phagocytic reactive oxygen species were not. The data also suggest a potential therapeutic role for antioxidants in airway hyperresponsiveness.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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