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  • Electronic Resource  (109)
  • Polymer and Materials Science  (101)
  • Rats  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Cyanophenoxy-containing microbial polyesters: Structural analysis, thermal properties, second harmonic generation and in-vivo biodegradability (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 39 (1996), S. 205-213 
    Details
    ISSN: 0959-8103
    Keywords: Pseudomonas putida ; poly(β-hydroxyalkanoate) ; microbial polyesters ; poly[3-hydroxy-6(4-cyanophenoxy)hexanoate] ; non-linear optics ; in-vivo biodegradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Pseudomonas putida KT 2442 was utilized as biocatalyst to form optoactive poly(β-hydroxyalkanoate)s (PHAs) from a cosubstrate mixture of octanoate and the achiral polarizable carbon source 6(4-cyanophenoxy)hexanoate, CPH. COSY and heteronuclear multiplet quantum correlation experiments were used to assign 1H and 13C NMR signals of 3-hydroxy-6(4-cyanophenoxy)hexanoate (3HCPH) repeat units. The methine carbon of 3HCPH repeat units was sensitive to repeat unit sequence effects, indicating that a substantial fraction of 3HCPH centered triad sequences in the product contain neighboring 3-hydroxyoctanoate and 3-hydroxhexanoate repeat units. Comparing the thermal properties of 0 and 19.6 mol% 3HCPH samples by differential scanning calorimetry shows that 3HCPH incorporation results in melting at temperatures 〉64°C (not seen for the 0 mol% sample), more rapid crystallization and a new Tg transition at ∼ -21°C. These characteristics indicate that chains and/or chain segments are formed that are enriched in 3HCPH which phaseseparate and form a unique crystal structure. Measurements of second harmonic generation (SHG) intensities carried out using in-situ corona-poled samples showed weak SHG signals that increased by a factor of 8 for an increase in the 3HCPH content from 26 to 34 mol%. Comparatively higher SHG intensities (5 times) were found for PHAs which contained 5.1 mol% 3-hydroxy-6(4-nitrophenoxy)hexanoate (3HNPH) repeat units relative to a PHA with 17 mol% 3HCPH. In-vivo biodegradation studies of microbial polyesters prepared with and without 3HCPH repeat units showed that PHA chains with 3HCPH degraded to lesser extents (weight loss of ∼ 20 and 50% over 72 h incubations). The large increase in polydispersity from 1.9 to 4.3 observed during in-vivo biodegradation of microbial polyesters containing 3HCPH repeat units was attributed to the existence of chains with highly variable contents of 3HCPH repeat units.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Concurrent etonitazene and water intake in rats: Role of taste, olfaction, and auditory stimuli (1979)
    Springer
    Psychopharmacology 64 (1979), S. 1-7 
    Details
    ISSN: 1432-2072
    Keywords: Etonitazene ; Etonitazene reinforcement ; Concurrent schedules ; Choice procedures ; Rats ; Taste ; Olfaction ; Auditory stimuli ; Discriminative stimuli ; Conditioned reinforcers ; Fixed-ratio schedules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Etonitazene and water were concurrently available to four rats during daily 1 h sessions in operant conditioning chambers equipped with two levers and two liquid dippers. A food-induced training procedure was used whereby etonitazene drinking was rapidly established by presenting rats with gradually increased drug concentrations with their daily food ration. When food was subsequently removed from the session and given post-session, etonitazene responding persisted. The rats were subsequently trained on fixed-ratio (FR) schedules with concurrent access to etonitazene and water. The number of dipper presentations compared with etonitazene concentrations (0.078–10.0 μg/ml) resulted in a typical inverted U-shaped function while etonitazene intake (μg/kg) increased directly with concentration. After drinking large quantities of etonitazene the rats showed ataxia, hyper-activity, and stereotypy. Extinction tests demonstrated that rats could discriminate between etonitazene and water on the basis of one dipper full of each liquid; the amount of etonitazene in one dipper was 0.0078 μg. Further tests showed that this discrimination was based on taste or immediate post-ingestional feedback rather than olfactory cues. An auditory stimulus was presented concurrently with responses on the drug lever; however, there was no difference in responding for the drug in the presence or absence of this stimulus except at the lowest concentration. After the extinction tests, when the lowest drug concentration was again available with concurrent water, responding was substantially higher in the presence of stimulus associated with availability of etonitazene. The results extend previous work on oral narcotic intake to a lever-press concurrent choice procedure which is sensitive to reinforcing effects of the drug at low concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427336
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  • 3
    Electronic Resource
    Electronic Resource
    The effects of feeding conditions on drug-reinforced behavior: Maintenance at reduced body weight versus availability of food (1980)
    Springer
    Psychopharmacology 68 (1980), S. 121-124 
    Details
    ISSN: 1432-2072
    Keywords: Etonitazene reinforcement ; Oral selfadministration ; Food deprivation ; Food access ; Concurrent schedules ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent research has shown that food deprivation increases drug self-administration in rats and rhesus monkeys. The purpose of the present study was to examine two variables related to this food-deprivation effect: maintenance of rats at reduced body weights and the absence of food. Etonitazene HCl was established as a reinforcer orally for 12 rats according to procedures previously used in experiments reported by this laboratory. Lever-pressing behavior was maintained under fixed-ratio (FR) schedules during daily 1-h sessions by etonitazene or water, which were available either concurrently or on alternating days. In the first experiment, six rats were maintained at 75% of their free-feeding weights. The effect of presenting the daily food allotment at 23, 4, 2, 1, or 0 h before their daily drug or water self-administration session was studied. When the rats were fed 23, 4, or 2 h before the session, etonitazene dipper presentations were at maximum levels and were substantially higher than for water. When the rats were fed during (0) or 1 h before the session, the number of etonitazene dipper presentations was lower, but it exceeded those for water. Under conditions of complete food satiation (0 h deprived-100% body weight), etonitazene and water dipper presentations were both low, and there were no differences between them. In the second experiment, six rats maintained at 75% of their free-feeding weights were trained to respond for etonitazene or water on alternating days. When they were subsequently food satiated (100% body weight), drug- and water-maintained behavior decreased to low levels. These rats were then deprived of food for 4 or 16 h before their daily 1-h session, and responding did not increase. Body weight did not decrease below 100%. These results suggest that maintenance at reduced body weight rather than the absence of food is the determinant of increased rates of drug-reinforced behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432128
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  • 4
    Electronic Resource
    Electronic Resource
    Ethanol-reinforced behavior of rats with concurrent access to food and water (1978)
    Springer
    Psychopharmacology 59 (1978), S. 7-11 
    Details
    ISSN: 1432-2072
    Keywords: Concurrent schedule ; Ethanol drinking ; Water drinking ; Food deprivation ; Food satiation ; Ethanol concentration ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Dippers filled with water or an ethanol solution were presented to male Wistar rats contingent on lever-pressing under a concurrent fixed-ratio 1 (water) fixed-ratio 1 (ethanol) schedule. During Phase I, when maintenance feedings were given during instead of following the daily 3-h sessions, the feedings increased drinking of both 8% (w/v) ethanol and water, with 8% ethanol being consumed in greater volumes than water. In Phase II, a 28-day transitional period from the food-deprived to the food-satiated state, continuous access to food during 3-h sessions moderately decreased 8% ethanol intake, and increased water intake and total liquid intake (water plus 8% ethanol). In Phase III, concurrent water and ethanol intake of food-satiated rats was compared over two identical series of ethanol concentrations (8, 11.3, 16, 22.6, 32, and 8% retest). Food was freely available in both the operant conditioning chambers and home cages. The number of dipper presentations of ethanol exceeded presentations of water for each rat at each concentration studied. Presentations of water were low in number and did not vary with the ethanol concentration. As the ethanol concentration was increased, the number of ethanol presentations decreased, while the quantity consumed (mg/100 g body weight/h) generally increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428023
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  • 5
    Electronic Resource
    Electronic Resource
    Determinants of increased drug self-administration due to food deprivation (1981)
    Springer
    Psychopharmacology 74 (1981), S. 197-200 
    Details
    ISSN: 1432-2072
    Keywords: Drug self-administration ; Food deprivation ; Etonitazene ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes in oral etonitazene self-administration were compared in four groups of rats that were maintained at 100, 95, 85, or 75% of their pre-experimental free-feeding body weights. Etonitazene (5 μg/ml) or water was available for 16 h according to a fixed-ratio (FR) 1 schedule. Each liquid delivery (0.1 ml) was contingent upon a lever-press response. During food deprivation etonitazene intake gradually increased to over two-fold as body weights decreased over 25 sessions; etonitazene intake was inversely proportional to body weight. The 75% weight group showed stereotypy, self-mutilation and large variability in daily etonitazene intake. In another experiment a range of deprivation conditions was studied in a group of six rats with etonitazene (5 μg/ml) or water available on an FR 8 schedule during 1-h sessions. When the rats were gradually food satiated, etonitazene-maintained behavior declined but remained higher than water-maintained behavior; however, when they were abruptly food satiated, etonitazene-maintained behavior decreased to low levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427092
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  • 6
    Electronic Resource
    Electronic Resource
    Ethanol as a reinforcer: Effects of fixed-ratio size and food deprivation (1973)
    Springer
    Psychopharmacology 28 (1973), S. 171-183 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00421402
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of scopolamine on variable intertrial interval spatial alternation and memory in the rat (1976)
    Springer
    Psychopharmacology 49 (1976), S. 131-137 
    Details
    ISSN: 1432-2072
    Keywords: Memory ; Storage ; Scopolamine ; Alternating discrimination ; Variable intertrial interval spatial alternation ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A repeated measures procedure, variable intertrial interval (ITI) spatial alternation, was used to assess scopolamine effects on memory, and to compare effects of the drug on discrimination processes with effects on storage. Rats learned in two stages to press left and right levers in alternation on discrete trials separated by 5 different ITI's ranging from 2.5 to 40 s and presented in random order during the experimental session. In the first stage, alternating discrimination, alternation was controlled by a light on over the correct lever at the time of the trial; in the second stage, variable ITI spatial alternation, a centrally located panel light signalled all trials and alternation was controlled by stimuli from prior trials (‘memory’). Alternation response occurrence declined moderately (but significantly) with increasing ITI duration in both the alternating discrimination and variable ITI spatial alternation stages; response occurrence was also significantly decreased by scopolamine treatment in both stages. Accuracy of alternating discrimination performance was not significantly altered by either ITI duration or scopolamine treatment. Accuracy of variable ITI spatial alternation performance on a trial varied inversely with the duration of the ITI that preceded the trial. Scopolamine treatment significantly reduced accuracy of lever pressing in variable ITI spatial alternation but did not alter the slope of the curves relating accuracy to ITI duration. These effects indicate that the drug impaired discrimination processes but did not alter memory storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427281
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  • 8
    Electronic Resource
    Electronic Resource
    Rapid establishment of ethanol as a reinforcer for rats (1974)
    Springer
    Psychopharmacology 37 (1974), S. 311-321 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00428917
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  • 9
    Electronic Resource
    Electronic Resource
    Ethanol as a reinforcer for rats: Effects of concurrent access to water and alternate positions of water and ethanol (1975)
    Springer
    Psychopharmacology 43 (1975), S. 19-23 
    Details
    ISSN: 1432-2072
    Keywords: Ethanol ; Ethanol Drinking ; Water-Ethanol Choice ; Concurrent Schedules ; Ethanol Concentration ; Ethanol Reinforcement ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Water and ethanol solutions were concurrently made available on a continuous reinforcement schedule to 4 food-deprived male albino rats during daily 1-hr sessions in an operant conditioning chamber equipped with 2 levers and 2 liquid dippers. The number of ethanol reinforcements substantially exceeded the number of water reinforcements for each rat at each concentration studied (8, 16, and 32% w/v). Water reinforcements were low in number and did not vary with ethanol concentration. As the ethanol concentration was increased, the number of ethanol reinforcements obtained decreased, while the quantity consumed (mg/100 g of body weight/hr) increased. The highest rate of responding occurred at the beginning of the session.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00437609
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  • 10
    Electronic Resource
    Electronic Resource
    Multiple denaturational transitions in fibrillar collagen (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 1875-1893 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heat denaturation of pepsinized bovine nonfibrillar and fibrillar collagen was studied by differential scanning calorimetry. For fibrillar preparations that had been rapidly precipitated with stirring at low ionic strength, then resuspended at physiological ionic strength, multiple denaturational transitions were observed. At heating rates of 10°C/min, melting endotherms occurred at about 44, 50, 53, and 57°C. Fibrillar collagen that was slowly gelled without stirring at physiological ionic strength exhibited a similar series of endotherms, but the lower melting transitions were less conspicuous. In contrast, nonfibrillar bovine collagen in acidic solution showed only a single denaturational transition at 40°C. Nonfibrillar solutions at pH 7, to which inhibitors of fibrillogenesis were added, showed a major endotherm as high as 46°C. These results suggest that reconstituted fibrillar collagen contains a heterogeneous fibril population, possibly including molecules in a nonfibrillar state. It was proposed that the multiple melting endotherms of such preparations were due to sequential melting of molecular and fibril classes, each with a distinct melting temperature. The fibrillar classes may represent three or more types of banded and nonbanded species that differ from each other in packing order, collagen concentration, and possibly also in fibril width and level of cross-linking.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360251006
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