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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 28 (1973), S. 171-183 
    ISSN: 1432-2072
    Keywords: Ethanol Drinking ; Ethanol Reinforcement ; Fixed-Ratio Size ; Food Deprivation ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats having prior experience with ethanol drinking were subjected to geometrically increasing fixed-ratio (FR) schedules of ethanol reinforcement (8% W/V). The rats were tested first food deprived and then food satiated. Each third day ethanol was the reinforcer (0.25 ml/reinforcement), while on other days water, which served as the vehicle control, was available. Food satiating the rats decreased responding for ethanol whereas responding for water was not changed. Under both food conditions ethanol maintained responding at FR's up to 256 with response totals exceeding water control values. As the FR size increased to intermediate values, the number of ethanol responses increased. Further FR increases resulted in decreases in ethanol responding. The pattern of FR responding was similar to that maintained by other reinforcers. Maximum ethanol responding occurred at the beginning of the 6-h sessions, followed by a pause and then intermittent bursts of responding. Water responding was not characterized by a specific pattern. It was inferred that the odor of ethanol functioned as a discriminative stimulus, and it was concluded that ethanol served as a reinforcer for the rat.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 28 (1973), S. 351-362 
    ISSN: 1432-2072
    Keywords: Ethanol ; Operant Performance ; Dose-Response Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of various doses of ethanol on DRL performance was examined in rats under conditions of cued and non-cued DRL tasks and under conditions of low versus high baseline performance criteria. The dose-level at which ethanol produced a significant reduction in number of responses and reinforcements interacted in a complex fashion with level of baseline performance, the cue conditions, and the order of DRL tasks. Generally, performance was impaired at a lower dose level for groups initially trained to a low criterion of DRL performance than for groups later trained to a higher criterion of DRL performance, regardless of cue condition. Further, the dose level at which ethanol impaired performance (as indicated by number of reinforcements obtained) under non-cued DRL conditions was lower than that for the cued DRL conditions, but only on the initial task where baseline DRL performance criterion was lower. Finally, the group with a higher baseline level of responding (i.e., poorer DRL performance) was more vulnerable to the disrupting effects of ethanol on this measure than groups with lower baseline response rates.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 37 (1974), S. 311-321 
    ISSN: 1432-2072
    Keywords: Rats ; Ethanol ; Ethanol Reinforcement ; Acquisition ; Schedule-Induced-Polydipsia ; Ethanol Concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Daily 6-h sessions were run during which each lever press by rats produced brief access to water, or to 8
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 132 (1972), S. 167-192 
    ISSN: 1432-0878
    Keywords: Microfilaments ; Contractility ; Morphogenesis ; Ascidians ; Cytochalasin B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During tail resorption in Distaplia occidentalis the caudal epidermis contracts to 8.5% of its initial length in about 6 minutes and forces the axial complex (muscle, notochord and nerve cord) into a coiled configuration in the trunk. The contraction of the caudal epidermal cells is accompanied by rapid alignment of arrays of circa 50 Å (diameter) filaments parallel to the axis of contraction in the apical cytoplasm of each epidermal cell. Normal metamorphosis (including tail resorption) can be instantly induced by treating tadpole larvae with 0.5% dimethylsulfoxide. Cytochalasin B, (CCB) 〉 0.25 μg/ml rapidly inhibits contraction of the caudal epidermis. The tail stops shortening, then partly re-extends. When CCB is removed by washing immediately after relaxation, tail resorption resumes. Cytochalasin B reversibly disrupts the organization of central and subterminal arrays of apical filaments in the contractile caudal epidermal cells. Membrane associated filaments near the junctional complexes are not disrupted by 0.25–1.0 μg/ml of CCB. This suggests that CCB does not degrade the filaments into subunits. It is more likely that CCB blocks contraction by disrupting the binding forces between overlapping filaments and facilitates the disorganization of unattached filaments. A second type of filament with a fusiform configuration has been detected in the epidermal cells after CCB treatment. The possibility that these are myosinoid proteins is considered. The data presented in this paper strengthen the hypothesis that the filaments in the epidermal cells are part of a contractile apparatus.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 107 (1970), S. 157-173 
    ISSN: 1432-0878
    Keywords: Ascidians ; Metamorphosis ; Blood cells ; Epidermis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During the first 10 minutes after the onset of metamorphosis in the ascidian Amaroucium constellatum there is a massive emigration of blood cells (granulocytes) from the hemocoel, across the epidermis, into the tunic. Electron microscopy has been employed to extend some of the classical observations of the last century. The new findings are compatible with the hypothesis that the blood cells follow a transcellular pathway. Our interpretation is as follows: an emigrating cell enters the basal part of an epidermal cell and becomes enclosed within a vacuole. The vacuole and the blood cell move to the apex of the epidermal cell. The vacuole fuses with the plasmalemma releasing the blood cell into the tunic. Blood cells can therefore pass through the epidermis without leaving a hole and without rupturing intercellular junctions.
    Type of Medium: Electronic Resource
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