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  • Electronic Resource  (10)
  • 1975-1979  (10)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 35 (1979), S. 559-582 
    ISSN: 1432-1106
    Keywords: Strabismus ; Amblyopia ; Retinal ganglion cells ; Visual acuity ; Contrast sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spatial resolving power, contrast sensitivity, and receptive field properties of retinal ganglion cells were studied in cats reared with either convergent or divergent squint in one eye. Sustained-X cells in the area centralis of the squinting eye of the cats with esotropia without alternating fixation showed significantly poorer spatial resolution, and reduced contrast sensitivity compared with cells in the area centralis of the normal eye. These amblyopic sustained-X cells in the area centralis of the squinting eye had receptive field characteristics similar to those found in immature cells of young kittens. They had a shallow sensitivity gradient within a relatively widespread centre zone and a weak and widespread inhibitory surround. In contrast, the sustained cells in the area centralis of the normal eye revealed a typical, well defined, small centre zone with its sensitivity gradient extremely steep and its inhibitory surround strong and confined. A minor degree of amblyopia was also found in transient Y-cells in the area centralis of the squinting eye of these cats. However, no loss of resolving power was found in the cells in the area centralis of the squinting eye of the cats with esotropia or exotropia which showed alternating fixation. Thus, amblyopia occurs in those eyes which have lost the use of the area centralis as the normal visual axis during early postnatal development, and its organic lesion is already apparent in the retinal ganglion cells — the third order neurone in the afferent visual system. It is suggested that the loss of the ability to fixate results in inadequate stimulation of the central retinal ganglion cells due to the habitual presence of blurred images at the area centralis which prevents their full development during the critical period.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 25 (1976), S. 63-77 
    ISSN: 1432-1106
    Keywords: Kitten LGN ; Single cell ; Convergent squint ; Visual acuity ; Amblyopia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 34 (1979), S. 11-26 
    ISSN: 1432-1106
    Keywords: Convergent squint ; Amblyopia ; Spatial vision in cat ; Contrast sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Visual acuity and contrast sensitivity were measured behaviourally in normal adult cats and cats reared with monocular convergent squint from 3, 6, 8, 12, and 24 weeks of age. The visual acuity of the squinting eye was significantly lower than that of the non-squinting eye in cats with squint from 3, 6, and 8 weeks of age. No significant difference in acuity between eyes was found in the 12- and 24-week squinting cats and in the controls. Contrast thresholds at all spatial frequencies tested (range 0.13–2.0 c/ °) were higher in the squinting eye than in the non-squinting eye of cats with squint from 3 and 6 weeks of age, but differences were greater at the higher spatial frequencies. In the 8-week squinting cat, contrast thresholds were increased only at higher spatial frequencies. No significant differences in contrast sensitivity were found in the cat with squint from 24 weeks of age and in the controls. The degree of disturbance of spatial vision in squinting cats was most related to the age at onset of the squint, i.e., the earlier the onset, the more profound the amblyopia. The period of susceptibility extended from about 3 to 12 weeks of age. When compared with data on the development of visual acuity in kittens, the pattern of results from the present study suggests that convergent squint can arrest the development of spatial vision.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 31 (1978), S. 193-206 
    ISSN: 1432-1106
    Keywords: Kitten LGN ; Development ; Visual acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1106
    Keywords: Kitten LGN ; Convergent squint ; Visual development ; Amblyopia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 6 (1979), S. 0 
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Ten inbred strains of mice were administrated with dinitrophenyl-bovine serum albumin (DNP-BSA) at a dose of 30 or 300 μg/day by continuous infusion technique. Anti-DNP plaque-forming cells (PFC) in their spleens were assayed 10 to 12 days after the beginning of the infusion. NZB, BALB/c, C3H/He and NC strains were high responders to both doses of DNP-BSA. KK, SII and TES strains were low responders: the antibody response was low to the dose of 30 μg/day, and high to the dose of 300 μg/day. Breeding tests between high responder BALB/c and intermediate responder DDD mice indicated that the immune response was largely controlled by a gene linked to the H-2 complex. Similar studies with high responder NZB and low responder TES mice suggested an involvement of a few genes: at least one of the controlling genes may be linked to the H-2 complex.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Child 5 (1979), S. 0 
    ISSN: 1365-2214
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Summary To answer the questions, (1) Which cells in the visual system are responsible for high visual acuity and (2) Does the function of the cells which provide high visual acuity develop postnatally; single cell studies have been made in the retina, lateral geniculate nucleus (LGN) and visual cortex of cats of different ages. Sustained-X retinal ganglion cells in the area centralis (the equivalent retinal position to the human fovea) set the upper limit of visual acuity. The cellular acuity develops postnatally until it reaches the adult level at 3–4 months-of-age. The improvement of acuity is associated with an increase in the strength of the inhibitory surround mechanism of the receptive field of sustained cells in the area centralis. The maturation of cellular acuity coincides with maturation of retinal and LGN synaptic organisation and of optic nerve myelination.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Reaction kinetics and catalysis letters 11 (1979), S. 149-153 
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Было установлено, что при восстановлении NO с помощью H2, MoO3−ZrO2 и Fe2O3−SiO2 являются наиболее активными среди всех десяти типов серий катализаторов Mo и Fe. На основе ИК-исследований было заключено, что высокая каталитическая активность вызвана способностью этих катализаторов образовывать адсорбированные частицы NO−.
    Notes: Abstract In the reduction of NO with H2, MoO3−ZrO2 and Fe2O3−SiO2 were found to be the most active among each ten kinds of a series of Mo and Fe catalysts. On the basis of an IR study, the high catalytic activities were conclued, to be caused by the ability of the catalysts to the formation of adsorbed NO− species.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 256 (1978), S. 398-398 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
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