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  • Cocaine  (4)
  • Life and Medical Sciences  (4)
  • Drug self-administration  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Behavioral economics of drug self-administration (1992)
    Springer
    Psychopharmacology 107 (1992), S. 211-216 
    Details
    ISSN: 1432-2072
    Keywords: Behavioral economics ; Drug self-administration ; Reinforcer interactions ; Concurrent reinforcers ; Cigarette smoking ; Coffee drinking ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In behavioral economics, consumption of a reinforcer is determined by its price and by the price of other available reinforcers. This study examined the effects of price manipulations on the consumption of concurrently available coffee and cigarettes. During fifteen 4-h sessions, coffee and cigarettes were concurrently available according to fixed-ratio (FR) schedules of reinforcement. After consumption stabilized under a fixed ratio 100 for both reinforcers, the response requirement for each reinforcer was varied separately (i.e., FR 100, 1000 and 2500), while the response requirement for the other reinforcer was kept at 100. Increasing the FR value decreased coffee and cigarette consumption to a similar degree. Also, as the price for cigarettes increased (and consumption decreased), coffee consumption decreased; however, as the price of coffee increased, cigarette consumption did not change. These results indicate that for this setting the reinforcing effects of cigarettes and coffee were comparable but interacted asymmetrically. These findings when analyzed and quantified via economic concepts of own-price and cross-price elasticity illustrate the viability of using behavioral economics to examine drug self-administration in a choice paradigm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245139
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  • 2
    Electronic Resource
    Electronic Resource
    Forced-choice versus free-choice procedures: Caffeine self-administration in humans (1992)
    Springer
    Psychopharmacology 109 (1992), S. 85-91 
    Details
    ISSN: 1432-2072
    Keywords: Caffeine ; Coffee ; Concurrent schedules ; Drug self-administration ; Humans ; Methodology ; Reinforcement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methodological comparisons of procedures for drug self-administration are rare. In studies examining the reinforcing effect of caffeine in humans, caffeine self-administration usually has been inferred from performance under forced-choice procedures. In the present experiment, caffeine self-administration via coffee was compared under forced-choice and free-choice conditions; i.e., when subjects were and were not required to use a minimum number of coffees. Ten moderate coffee drinkers (2–7 cups/day) were assigned to forced- and free-choice conditions using a randomized cross-over design. Under each choice condition, subjects completed six independent, double-blind trials, consisting of a 2-day exposure period followed by a 2-day test period. During exposure, subjects consumed either decaffeinated or caffeinated (100 mg/serving) coffee on day 1 and the other coffee on day 2. During the test period, subjects had concurrent access to the same decaffeinated and caffeinated coffees. Under the forced-choice condition, subjects were required to drink at least four cups of coffee per day during the test period. Under the free-choice condition, subjects did not have a minimum-cup requirement. In general, the relative rate at which subjects self-administered caffeinated versus decaffeinated coffee was similar across choice conditions, even though subjects self-administered significantly fewer cups of both coffee types under the free-choice than the forced-choice condition. These results suggest that, at least for caffeine, forced-choice and free-choice procedures produce comparable results. Whether this finding generalizes to a context in which caffeine or another drug is more robustly self-administered, remains to be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245484
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  • 3
    Electronic Resource
    Electronic Resource
    Acute behavioral and cardiac effects of cocaine and alcohol combinations in humans (1993)
    Springer
    Psychopharmacology 111 (1993), S. 285-294 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Alcohol ; Drug interactions ; Psychomotor performance ; Heart rate ; Humans ; Cardiac effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Subjects received acute doses of orally administered alcohol (0–1.0 g/kg) and intranasal cocaine (4–96 mg/70 kg) alone and in combination in two experiments. Results generally were consistent across both experiments. Cocaine administered alone improved Digit Symbol Substitution Test (DSST) performance, increased subject ratings of stimulant-like effects, heart rate and blood pressure, and decreased skin temperature. Alcohol administered alone disrupted DSST performance, increased ratings of drunkenness, heart rate and skin temperature, and decreased blood pressure. Combining cocaine and alcohol attenuated the disruptions in DSST performance observed with alcohol alone, and either did not change or attenuated the improvements in performance observed with cocaine alone. Combining the drugs also attenuated effects observed with the drugs alone on skin temperature and, to a lesser extent, blood pressure. By contrast, drug combinations increased heart rate above levels observed when cocaine or alcohol were administered alone. Effects of the drug combinations on subject ratings were variable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244943
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  • 4
    Electronic Resource
    Electronic Resource
    Alcohol pretreatment increases preference for cocaine over monetary reinforcement (1996)
    Springer
    Psychopharmacology 123 (1996), S. 1-8 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Alcohol ; Self-administration ; Choice ; Heart rate ; Cardiac function ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Non-dependent cocaine users participated in a two-phase experiment conducted under controlled laboratory conditions. During phase 1, subjects sampled intranasal cocaine (100 mg) and placebo (96 mg lactose +4 mg cocaine) in separate sessions and under double-blind conditions. Sampling sessions were followed by a single choice session in which subjects made a maximum of ten choices between 10 mg unit doses of cocaine or placebo. Only subjects who reliably (≥70%) chose cocaine over placebo in phase 1 participated in phase 2. During phase 2, subjects participated in a series of nine experimental sessions conducted on different days in which they were pretreated with varying doses of alcohol (placebo, 0.5, and 1.0 g/kg) and made a maximum of ten choices between 10 mg unit doses of cocaine and an alternative reinforcer (i.e., varying amounts of money). Visual-analog ratings of drug effects and cardiac function were monitored across all experimental sessions. Cocaine was reliably chosen over placebo by the majority (9 of 11) of subjects during phase 1, demonstrating that the drug functioned as a reinforcer. During phase 2, alcohol pretreatment significantly increased choice of cocaine over the alternative reinforcer, while increasing monetary value decreased cocaine choice. Ratings on some visual-analog scales (e.g., good effects) paralleled cocaine choice, with alcohol pretreatment increasing ratings and greater monetary value decreasing them. Cardiac output increased above baseline levels across all alcohol and monetary conditions, but maximal effects were observed during sessions involving pretreatment with the active alcohol doses. Overall, these results demonstrate (a) that alcohol can increase preference for cocaine over alternative reinforcers and thereby may thwart efforts to reduce or abstain from cocaine use, (b) that availability of an alternative, non-drug reinforcer can effectively decrease preference for cocaine, and (c) that combined use of alcohol and cocaine increases cardiac risk compared to use of cocaine alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246274
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of intranasal cocaine on human learning, performance and physiology (1990)
    Springer
    Psychopharmacology 102 (1990), S. 451-458 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Psychomotor performance ; Learning ; Heart rate ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The behavioral and physiological effects of intranasally administered cocaine (placebo, 48, 96 mg/70 kg) were examined in eight recreational cocaine users under controlled laboratory conditions. The 48 and 96 mg doses of cocaine significantly improved subjects' performance on the Digit Symbol Substitution Test above levels observed either prior to drug administration or when placebo was administered. These effects were discernible for up to 120 min after cocaine administration. Cocaine had no statistically significant effects on learning and performance of ten-response sequences. The 48 and 96 mg doses increased heart rate and blood pressure for up to 180 min, and increased subject ratings of drug effects and decreased skin temperature for 60–90 min after drug administration. Cocaine produced no significant effects on the electrocardiogram. To our knowledge, this is the first experimental demonstration that acutely administered cocaine can improve behavioral performance in rested subjects. In addition, the duration of cardiac effects in this study was longer than previously reported with intranasal cocaine, perhaps due to the concurrent behavioral testing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247124
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  • 6
    Electronic Resource
    Electronic Resource
    The behavioral economics of concurrent drug reinforcers: a review and reanalysis of drug self-administration research (1995)
    Springer
    Psychopharmacology 118 (1995), S. 250-259 
    Details
    ISSN: 1432-2072
    Keywords: Behavioral economics ; Caffeinated coffee ; Cocaine ; Complements ; Concurrent schedules of reinforcement ; Cross-price elasticity ; Ethanol ; Etonitazene ; Drug self-administration ; Heroin ; Food ; Methadone ; Morphine ; Nicotine cigarettes ; Pentobarbital ; Phencyclidine ; Reinforcer interactions ; Substitutes ; Sucrose ; Water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In economics, goods can function as substitutes, complements, or be independent of one another. These concepts refer to increases, decreases, or no change in the consumption of one item as the price of a second item increases. This review examined whether these economic terms can be used to describe relationships between concurrently available reinforcers in drug self-administration research. Sixteen drug self-administration studies that examined the effects of concurrent reinforcers were identified through a MEDLINE search. Across these studies, the following substances were employed: caffeinated coffee, cocaine, etonitazene, ethanol, heroin, food, methadone, morphine, nicotine cigarettes, pentobarbital, phencyclidine, sucrose and water. These studies were reanalyzed and the results were shown to be consistent with these economic notions. These analyses also showed that relationships among the concurrently available reinforcers were reliable within and across studies, that concurrently available reinforcers can affect each other asymmetrically, and that the relative price may determine the magnitude of effect for substitutes. These findings suggest that these economic concepts may be useful in characterizing the type and magnitude of interactions between concurrently available reinforcers and may suggest potential mechanisms that determine these relationships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245952
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  • 7
    Electronic Resource
    Electronic Resource
    Struktur, Funktion und Evolution der ATPasen (1992)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 22 (1992), S. 157-162 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Eines der frühesten Probleme unter den ersten lebenden Zellen war die Bewältigung der „osmotischen Krise“. Diese entstand durch den Einstrom von Ionen und Wasser durch die semipermeable Plasmamembran ins Innere der Zellen, zu den dort eingeschlossenen Makromolekülen. Die Lösung des Problems konnte nur durch aktives Ausschleusen von Ionen erreicht werden, also mit Hilfe von Ionenpumpen. Zu den wichtigsten Ionenpumpen in der Natur gehören die ATPasen. Sie kommen in allen Lebewesen vor, vom Bakterium bis zum Menschen. Unter den ATPasen spielen die protonenpumpenden eine zentrale Rolle im Stoffwechsel: Sie stellen einen Protonengradienten zwischen verschiedenen Kompartimenten der Zelle her, und dieser wiederum ist der Antrieb für den wichtigsten Prozeß innerhalb eines Lebewesens, nämlich die Speicherung von chemischer Energie in Form von ATP.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19920220321
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  • 8
    Electronic Resource
    Electronic Resource
    Holding chromatids together to ensure they go their separate ways (1996)
    New York, NY : Wiley-Blackwell
    BioEssays 18 (1996), S. 293-300 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Association between sister chromatids is essential for their attachment and segregation to opposite poles of the spindle in mitosis and meiosis II. Sister-chromatid cohesion is also likely to be involved in linking homologous chromosomes together in meiosis I. Cytological observations provide evidence that attachment between sister chromatids is different in meiosis and mitosis and suggest that cohesion between the chromatid arms may differ mechanistically from that at the centromere. The physical nature of cohesion is addressed, and proteins that are candidates for holding sister chromatids together are discussed. Dissolution of sister-chromatid cohesion must be regulated precisely, and potential mechanisms to release cohesion are presented.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950180407
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  • 9
    Electronic Resource
    Electronic Resource
    Thermographie einer erwachenden Fledermaus (1994)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 24 (1994), S. 129-130 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19940240308
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  • 10
    Electronic Resource
    Electronic Resource
    Leben im Salz  -  Halophile Archaea (1995)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 25 (1995), S. 380-389 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Der größte Teil des Wassers auf diesem Planeten ist Meerwasser, welches eine relativ konstante Zusammensetzung anorganischer Salze enthält. In hypersalinen Gewässern dagegen sind höhere Salzkonzentrationen als im normalen Meerwasser vorhanden. Überall dort, wo die Verdunstungsrate großer ist als der Wasserzufluß, in küstennahen Regionen der Meere, zum Beispiel in flachen Lagunen, aber auch in einigen großen Inlandseen, wie zum Beispiel dem Great Salt Lake in Utah, liegen zwar ähnliche Verhältnisse der anorganischen Ionen untereinander, aber insgesamt höhere Konzentrationen als im durchschnittlichen Meerwasser vor. Hier handelt es sich um die thalassohalinen (griechisch: thalassos = Meer) Standorte, entstanden durch Wasserverlust, ohne daß das Löslichkeitsprodukt für eine Komponente der Salze überschritten wird. Die Gesamtsalinität eines thalassohalinen Gewässers kann von 3,4 % (Gewicht pro Volumen) in normalem Meerwasser bis zu 49 % schwanken. In Salzgewinnungsteichen fällt Natriumchlorid (NaCl) ab etwa 37 % aus, während die leichter löslichen Magnesium-(MgCl2) und Kaliumchloride (KCl) sich in der Lösung anreichern. Ab diesem Punkt entspricht das Wasser nicht mehr dem Begriff „thalassohalin“, da sich die Salzverhältnisse ändern.Je höher die Salzkonzentration ist, desto mehr verschwinden höhere Lebensformen. Sie werden durch angepaßte Mikroorganismen ersetzt. Bis zu einer Salinität von 7,5 % findet man noch einige salztolerante Fische, ab 13 % ist kein Fisch mehr in der Lage zu überleben. Die einzigen makroskopischen Organismen, die im Bereich von 10-30 % relativem Salzgehalt vorkommen, sind das Salinenkrebschen Artemia salina und die Larve der Salzfliege Ephydra speciae Das Phytoplankton besteht in diesem Bereich hauptsächlich aus der einzelligen, photosynthetisch aktiven Grünalgengattung Dunaliella. In den Salinenbecken schließlich, im Präzipitationsbereich von NaCl, findet man fast ausschließlich Halobakterien [14].
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19950250624
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