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  • 1
    Electronic Resource
    Electronic Resource
    On the interaction between anhysteretic magnetization and demagnetizing fields in iron strips (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 1838-1846 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Anhysteretic magnetization is the magnetization that results if a constant bias field and an alternating field with decreasing amplitude are applied simultaneously to a ferromagnetic sample. Both anhysteretic magnetization and magnetization curves were measured on strips of iron shielding material in two cases where the product of the demagnetization factor and magnetization is much smaller than or comparable with the external field. The influence of demagnetizing fields on the measured effective anhysteretic permeability can be described neither by "normal'' shearing of the magnetization curve nor by a dependence predicted by Néel for anhysteretic permeability. A crucial role in Néel's theory is played by so-called "frozen magnetization.'' During anhysteretic magnetization an increasing fraction of the magnetization ceases to follow the applied alternating field and remains fixed. Comparison with Preisach models suggests that deviation from normal behavior is connected with a gradual rather than an instantaneous buildup of frozen magnetization. It is concluded that Néel's theory gives a qualitative but not a quantitative explanation of the dependence of anhysteretic permeability on demagnetizing fields in the material investigated. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364009
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  • 2
    Electronic Resource
    Electronic Resource
    Non-specific effect of naltrexone on ethanol consumption in social drinkers (1999)
    Springer
    Psychopharmacology 146 (1999), S. 33-41 
    Details
    ISSN: 1432-2072
    Keywords: Key words Ethanol ; Social drinker ; Naltrexone ; Opioid antagonist ; Preference ; Subjective effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Clinical studies have shown that the opioid antagonist naltrexone is effective in the treatment of alcoholism. However, the mechanism by which it produces this effect is not understood. Objective: This study was designed to investigate the effect of acute naltrexone on consumption of ethanol in healthy, non-problem social drinkers. Methods: Subjects (n=24) participated in an eight-session, within-subject, placebo-controlled choice procedure which measured ethanol preference and consumption. The procedure consisted of two blocks of four sessions in which subjects received either naltrexone (50 mg oral) or placebo 1 h before consuming an ethanol or placebo beverage. On the first two sessions of each block, subjects received a color-coded beverage containing ethanol (0.75 g/kg) or placebo, in five equal portions at 15-min intervals. On the next two sessions of each block, subjects chose which beverage they preferred (i.e., placebo or ethanol) and how much they wished to take, in unit doses (placebo or ethanol 0.15 g/kg/dose). The primary behavioral measures were (1) the number of times subjects chose ethanol over placebo, and (2) the number of doses they consumed. Subjects rated their mood states and subjective drug effects at regular intervals during each session. Results: Naltrexone did not alter the frequency of ethanol (versus placebo) choice. Although naltrexone did decrease the total number of ethanol doses subjects took (mean 2.7 doses after naltrexone; 3.4 doses after placebo), it also decreased the number of placebo ”doses” subjects took on sessions when they chose the placebo beverage (mean 1.6 placebo doses after naltrexone; 2.8 doses after placebo). Ethanol produced its prototypic subjective effects (e.g., increased ratings of ”feel drug”, ”like drug” and ”high”), and these effects were not altered by naltrexone. Naltrexone produced mild sedative-like effects, and several subjects reported adverse effects such as nausea. Conclusions: These findings show that naltrexone reduces ethanol consumption in healthy volunteers, as it does in alcoholics. However, this reduction was not specific to alcohol; subjects also consumed less of a non-alcoholic, placebo beverage. These findings suggest that naltrexone may reduce alcohol consumption by a non-specific mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130051085
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  • 3
    Electronic Resource
    Electronic Resource
    Notice of Special Issue of Psychopharmacology: ”Drugs and impulsivity: current theories, methods and results” (1998)
    Springer
    Psychopharmacology 140 (1998), S. 249-249 
    Details
    ISSN: 1432-2072
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050764
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  • 4
    Electronic Resource
    Electronic Resource
    Interaction of expectancy and the pharmacological effects ofd-amphetamine: subjective effects and self-administration (1996)
    Springer
    Psychopharmacology 125 (1996), S. 371-378 
    Details
    ISSN: 1432-2072
    Keywords: Balanced placebo design ; Expectancy ; d-Amphetamine ; Subjective effects ; Self-administration ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The study examined the effects of expectation on the subjective effects and oral self-administration of 15 mgd-amphetamine (AMP) and placebo in 40 volunteers who reported no prior use of stimulants other than caffeine. A balanced placebo design was used to create four groups: told Placebo/got Placebo (P/P), told Placebo/got Stimulant (P/S), told Stimulant/got Placebo (S/P), told Stimulant/got Stimulant (S/S). There were three sessions. On one session (INFO), participants received a capsule containing AMP or placebo and were given information about the contents of the capsule according to the balanced placebo design. On another session (NO INFO), participants received no information about the capsule's contents and were given placebo. On the final session, participants were allowed to choose either the INFO or NO INFO capsule. Participants came to the laboratory to ingest their capsules, and then returned to their normal environments where they completed subjective effects questionnaires every 2 h for 8 h. Expectancies influenced the subjective effects reported during the INFO session, regardless of whether subjects actually received AMP or placebo: subjects who expected a stimulant had higher ratings of “feel drug” and “like drug”. The pharmacological effects of AMP were also evident on the INFO sessions: AMP produced its prototypic subjective effects regardless of subjects' expectancies. Significant interactions between drug and expectancy were obtained on self-report measures of anxiety and arousal: anxiety was higher for groups who received substances that did not match their expectations (P/S and S/P) and arousal increased most in volunteers who expected placebo but received stimulant. Choice of drug was determined primarily by pharmacology: participants who received AMP on the INFO session usually chose that capsule, regardless of information about its identity (P/S: 8/10; S/S: 9/10). In contrast, participants who received placebo on the INFO session chose this capsule at chance levels, regardless of information about its identity (S/P: 3/10; P/P: 6/10). Thus, expectancy influenced some of the subjective effects of AMP and placebo, but the pharmacological effects of the AMP were instrumental in determining whether volunteers would self-administer the drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246020
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  • 5
    Electronic Resource
    Electronic Resource
    Acute effects of d-amphetamine during the follicular and luteal phases of the menstrual cycle in women (1999)
    Springer
    Psychopharmacology 145 (1999), S. 67-75 
    Details
    ISSN: 1432-2072
    Keywords: Key words Menstrual cycle ; Estrogen ; Progesterone ; d-Amphetamine ; Subjective effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rationale: Little is known about the interactions between ovarian hormones across the menstrual cycle and responses to psychoactive drugs in humans. Preclinical studies suggest that ovarian hormones such as estrogen and progesterone have direct and indirect central nervous system actions, and that these hormones can influence behavioral responses to psychoactive drugs. Objectives: In the present study, we assessed the subjective and behavioral effects of d-amphetamine (AMPH; 15 mg orally) at two hormonally distinct phases of the menstrual cycle in women. Methods: Sixteen healthy women received AMPH or placebo capsules during the follicular and mid-luteal phases of their cycle. During the follicular phase, estrogen levels are low initially and then rise while progesterone levels remain low. During the mid-luteal phase, levels of both estrogen and progesterone are relatively high. Dependent measures included self-report questionnaires, physiological measures and plasma hormone levels. Results: Although there were no baseline differences in mood during the follicular or luteal phase, the effects of AMPH were greater during the follicular phase than the luteal phase. During the follicular phase, subjects reported feeling more “High”, “Energetic and Intellectually Efficient”, and “Euphoric” after AMPH than during the luteal phase, and also reported liking and wanting AMPH more. Further analyses showed that during the follicular phase, but not the luteal phase, responses to AMPH were related to levels of estrogen. Higher levels of estrogen were associated with greater AMPH-induced increases in “Euphoria” and “Energy and Intellectual Efficiency”. During the luteal phase, in the presence of both estrogen and progesterone, estrogen levels were not related to the effects of AMPH. Conclusions: These findings suggest that estrogen may enhance the subjective responses to a stimulant drug in women, but that this effect may be masked in the presence of progesterone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130051033
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of setting on the reinforcing and subjective effects of ethanol in social drinkers (1995)
    Springer
    Psychopharmacology 118 (1995), S. 19-27 
    Details
    ISSN: 1432-2072
    Keywords: Ethanol ; Reinforcing effects ; Choice Subjective drug effects ; Setting ; Social ; Isolated Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The reinforcing and subjective effects of two doses of ethanol [0.5 g/kg (LOW) and 0.8 g/kg (HIGH)] were evaluated under two conditions, a social condition (SOC), in which subjects were tested with two or three other subjects, and a socially isolated condition (ISO), in which subjects were tested alone. Forty-one social drinkers participated in a double-blind, seven-session choice procedure. Subjects were randomly assigned to one of four experimental groups: SOC-LOW, SOC-HIGH, ISO-LOW, or ISO-HIGH. On the first four sessions, subjects sampled ethanol (0.5 or 0.8 g/kg) on two occasions and placebo on the other two occasions. On the three remaining sessions, subjects selected and consumed whichever of the two previously sampled substances they preferred. The number of sessions on which they chose ethanol was the primary measure of the reinforcing effects of ethanol. Standardized self-report questionnaires and a psychomotor test were used to measure subjective and objective drug effects. Subjects in the SOC condition chose ethanol over placebo on significantly more sessions than subjects in the ISO condition. Ethanol produced positive subjective effects (e.g., increased ratings of drug liking and euphoria) for subjects in the SOC condition, but for subjects in the ISO condition, it produced apparently negative effects (e.g., increased ratings of dysphoria). These results extend previous reports that the behavioral effects of ethanol depend upon the social condition in which it is consumed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245245
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  • 7
    Electronic Resource
    Electronic Resource
    Preference for diazepam, but not buspirone, in moderate drinkers (1996)
    Springer
    Psychopharmacology 123 (1996), S. 154-163 
    Details
    ISSN: 1432-2072
    Keywords: Anxiolytic ; Diazepam ; Buspirone ; Self-administration ; Abuse liability ; Drug abuse ; Subjective effects ; Choice ; Reinforcement ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the present study was to determine the preference for buspirone, an anxiolytic predicted to have minimal abuse potential, in comparison with diazepam in moderate drinkers. Preference for diazepam and buspirone was assessed in 55 moderate drinkers using a seven-session procedure consisting of four sampling sessions followed by three choice sessions. On each sampling session subjects ingested five capsules, one every 30 min. Color-coded capsules contained placebo on two sessions and drug on two sessions. Each drug capsule contained diazepam (4 mg) for 30 subjects and buspirone (5 mg) for 25 subjects. On choice sessions subjects chose whichever of the two color-coded capsules, i.e., drug or placebo, they wished to take. After ingesting one capsule, every 30 min they had the option of ingesting another capsule of the same color and content, for a maximum of seven capsules over the session (maximum of 28 mg diazepam or 35 mg buspirone). In the diazepam group 70% of subjects chose diazepam over placebo on at least two of the three choice sessions, whereas in the buspirone group only 24% of subjects chose buspirone over placebo on at least two sessions. Both diazepam and buspirone increased measures of sedation. Only diazepam increased ratings of liking and impaired performance, whereas only buspirone decreased ratings of feeling Friendly. These results replicate previous findings indicating that diazepam has reinforcing effects in moderate drinkers. Further, these results demonstrate the pharmacological specificity of this effect by showing that buspirone did not function as a reinforcer under these same conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246172
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  • 8
    Electronic Resource
    Electronic Resource
    Acute effects of triazolam in women: relationships with progesterone, estradiol and allopregnanolone (1997)
    Springer
    Psychopharmacology 130 (1997), S. 69-78 
    Details
    ISSN: 1432-2072
    Keywords: Key words Menstrual ; Hormones ; Benzodiazepine ; Allopregnanolone ; Subjective effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study investigated hormone levels and mood in normal women to explore relationships between levels of circulating hormones and i) baseline mood states and ii) effects of triazolam on mood. Certain ovarian hormones or their metabolites have direct actions on neuronal receptors. These actions may result in changes in mood state, or changes in responses to psychoactive drugs which act on the same receptors. The present study explored relationships between estrogen, progesterone and a metabolite of progesterone, allopregnanolone, and the mood-altering and performance effects of an acute dose of triazolam. Triazolam is a short-acting benzodiazepine which acts via the GABAA receptor complex. Twenty women received triazolam (0.25 mg) or placebo at the follicular, ovulatory and luteal phases of their menstrual cycle. Each subject participated in six conditions (i.e., drug and placebo at each of the three phases), across two menstrual cycles. Dependent measures included self-reported mood states, psychomotor performance, and plasma levels of estradiol, progesterone, allopregnanolone, and triazolam. Mood and performance measures were not clearly related to hormone levels when data from all three phases were examined. However, within the luteal phase, higher levels of allopregnanolone were associated with lower self-reported arousal before any drug administration (i.e., at baseline). After administration of triazolam, most subjects reported the expected decreases in ratings of arousal. However, the subjects with the highest levels of allopregnanolone reported increases in ratings of arousal. Thus, hormone levels were related to mood and responses to triazolam, particularly during the luteal phase of the cycle. However, the drug-hormone interactions on mood and behavior were complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050212
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of methamphetamine on the adjusting amount procedure, a model of impulsive behavior in rats (1999)
    Springer
    Psychopharmacology 146 (1999), S. 432-439 
    Details
    ISSN: 1432-2072
    Keywords: Key words Impulsivity ; Choice ; Delay ; Methamphetamine ; Drug abuse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Moderate doses of d-amphetamine (given both acutely and chronically) have been shown to decrease impulsivity in children with attention deficit hyperactivity disorder (ADHD) and to improve attention and learning in normal adults. In contrast, chronic doses of methamphetamine (METH) in drug abusers have been associated with increased impulsivity, and impairments in learning and attention. Objectives: We report the effects of METH on an animal model of impulsive behavior. Methods: Rats were tested using the adjusting amount (AdjAmt) procedure in which the animals choose between a delayed fixed (large) amount of water and an immediate adjusting (small) amount of water. In the acute METH study, rats were given a single dose of 0.5, 1.0, 2.0, and 4.0 mg/kg METH or saline 30 min before testing. In the chronic METH study, we determined the effects of the 4.0 mg/kg dose of METH injected chronically 1 h after behavioral testing for 14 days. Thus the rats were tested using the AdjAmt procedure 22 h after injections of METH or saline. Results: After 0.5, 1.0 and 2.0 mg/kg METH, the rats valued the delayed large rewards more than after saline, indicating that the METH decreased impulsiveness. At the 4.0 mg/kg dose, the rats failed to respond. Rats treated repeatedly with the post-session large behaviorally disruptive dose of METH valued the delayed large rewards less than the saline-treated rats, indicating that this dosing regimen of METH increased impulsiveness. Conclusions: In these experiments, the rats became less impulsive after acute non-disruptive doses of pre-session METH, whereas they became more impulsive after receiving repeated post-session injections of a dose that was behaviorally disruptive when administered acutely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005488
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  • 10
    Electronic Resource
    Electronic Resource
    New technique for kla measurement between gas and water in aerated solvent-in-water dispersions (1996)
    Springer
    Biotechnology techniques 10 (1996), S. 195-198 
    Details
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new technique is presented to determine gas-to-water overall volumetric mass transfer coefficients (k l a) in a stirred-tank reactor containing solvent-in-water dispersions. The compound to be transferred from the gas to the water was toluene; the water-immiscible organic solvent was FC40, a perfluorocarbon. The k l a was determined in steady-state conditions in the absence of biological consumption. Toluene removal was achieved by passing a continuous flow of toluene-free water through the reactor. When solvent was present it was separated from the water at the reactor outlet by means of a small settler and recycled back to the vessel. The k l a was found to increase with the FC40 volume fraction. An enhancement of 1.9 times on an aqueous-phase-volume basis was found at 15 % (v/v) FC40.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00158945
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