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  • 1
    Electronic Resource
    Electronic Resource
    The discriminative stimulus properties and detection thresholds of intracranial self-stimulation: Effects of d-amphetamine, morphine, and haloperidol (1985)
    Springer
    Psychopharmacology 85 (1985), S. 289-294 
    Details
    ISSN: 1432-2072
    Keywords: Discriminative stimulus properties ; ICSS detection thresholds ; d-Amphetamine ; Morphine ; Haloperidol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A two-choice discrimination task was used to evaluate the effects of psychoactive drugs on the discriminative stimulus properties of brain self-stimulation in rats. In these experiments, brain stimulation served both as a discriminative stimulus and as a reinforcing stimulus, but the two effects were manipulated separately. Animals were trained to a criterion of 95% correct in choosing between two levers, and when this levels of accuracy was reached, the ability to choose correctly remained stable over an 8-month period. Increasing the current strength of the discriminative stimulus from zero to 100% of the training current produced a graded increase in the number of trials completed on the appropriate lever. The discriminative effects produced by brain stimulation were evaluated pharmacologically by using three prototypical psychoactive drugs in an attempt to change the detection threshold for the discriminative stimulus. Morphine, d-amphetamine, and haloperidol, drugs that reliably alter reinforcement thresholds for brain stimulation, failed to change detection thresholds. These results demonstrated that: (1) brain stimulation produces potent and reliable discriminative effects and (2) the effects of psychoactive drugs on detection thresholds can be dissociated from their effects on reinforcement thresholds for brain stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428189
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  • 2
    Electronic Resource
    Electronic Resource
    Threshold differences for naloxone and naltrexone in the hypothalamus and midbrain using fixed ratio brain self-stimulation in rats (1981)
    Springer
    Psychopharmacology 74 (1981), S. 17-22 
    Details
    ISSN: 1432-2072
    Keywords: Brain self-stimulation ; Fixed ratio reinforcement ; Morphine ; Naloxone ; Naltrexone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were implanted with stimulating electrodes aimed either at the medial forebrain bundle-lateral hypothalamus (MFB-LH) or the midbrain-central gray (MID-GG), and were trained to lever-press for brain self-stimulation on a fixed ratio: 15 schedule of reinforcement. The dose-dependent effects of morphine (0.1–3.0 mg/kg), naloxone (0.1–30 mg/kg), and naltrexone (0.1–30 mg/kg) were then determined during 1 h test sessions. Both naloxone and naltrexone decreased the rate of responding in the MFB-LH as well as in the MID-CG. However, decrements in response rates were produced in the MID-CG by both naloxone and naltrexone at one tenth the doses required to produce similar decrements with electrodes in the MFB-LH. Dose-dependent decreases in response rates produced by morphine occurred at the same doses in the two electrode sites. At both sites, the decreases in response rates produced by the highest dose of morphine were antagonized completely by a low dose of naloxone (0.1 mg/kg). At an intermediate dose of naloxone (1.0 mg/kg), antagonism occurred in the MFB-LH but not in the MID-CG. At a high dose of naloxone (10 mg/kg), a depression in lever-pressing occurred at both sites in the morphine-treated animal indicating that the depressive action predominated over antagonism. These data explain the lack of consistency of the effects of naloxone on brain self-stimulation previously reported by different laboratories, and demonstrate that the use of partial reinforcement schedules in a rational approach to the evaluation of opioid effects on brain self-stimulation behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431750
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  • 3
    Electronic Resource
    Electronic Resource
    Formation of the amphibian grey crescent: Effects of colchicine and cytochalasin B (1978)
    Springer
    Development genes and evolution 185 (1978), S. 99-104 
    Details
    ISSN: 1432-041X
    Keywords: Amphibian ; Grey crescent ; Colchicine ; Cytochalasine B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of colchicine and cytochalasin B on grey crescent formation in frog (Rana pipiens) and toad (Bufo arenarum) eggs were determined. Colchicine prevented the appearance of the grey crescent, but this inhibition was not due to the absence of an aster. Cytochalasin B did not inhibit grey crescent formation, nor did it inhibit certain activation events such as cortical granule breakdown or cortical contraction. Cytochalasin B caused a detachment of the cortex from the cytoplasm and induced the formation of a morphological grey crescent in non-activated eggs. The results suggest that microtubules may play several roles in grey crescent formation and that a change in the attachment of the cortex to the cytoplasm may also be involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848218
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  • 4
    Electronic Resource
    Electronic Resource
    Ultraviolet light inhibits grey crescent formation on the frog egg (1980)
    Springer
    Development genes and evolution 189 (1980), S. 73-76 
    Details
    ISSN: 1432-041X
    Keywords: Ultraviolet irradiation ; Amphibian ; Grey crescent ; Embryology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Work by others has shown that ultraviolet (UV) irradiation of the vegetal half of the uncleaved frog egg causes defects in neural development. We find that the earliest effect of irradiation ofRana pipiens eggs is to prevent grey crescent formation, the first indication of dorso-ventral polarization of the egg. The UV effect on the grey crescent and on neural development shows similarities in timing, dose-responses, and reversal by cold. We suggest that the UV effect on neural morphogenesis may be caused by the inhibition of cortical-cytoplasmic movement involved in grey crescent formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848569
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  • 5
    Electronic Resource
    Electronic Resource
    Interactions of naloxone with morphine, amphetamine and phencyclidine on fixed interval responding for intracranial self-stimulation in rats (1990)
    Springer
    Psychopharmacology 102 (1990), S. 263-268 
    Details
    ISSN: 1432-2072
    Keywords: Fixed interval: 60 s schedule ; Intracranial self-stimulation ; Naloxone ; Morphine ; d-Amphetamine ; Phencyclidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were implanted with stimulating electrodes aimed at the medial forebrain bundle-lateral hypothalamus (MFB-LH) and were trained to lever-press for brain self-stimulation on a fixed interval: 60 s schedule of reinforcement. The effects of graded doses of naloxone (0.1–30 mg/kg), morphine (0.3–5.6 mg/kg), naloxone plus morphine,d-amphetamine (0.03–1.0 mg/kg), naloxone plusd-amphetamine, phencyclidine (0.3–5.6 mg/kg), and naloxone plus phencyclidine were tested. Naloxone produced a significant decrease in rates at 30 mg/kg. Naloxone (0.1–1.0 mg/kg) plus morphine blocked the dose-dependent decrease produced by morphine alone. In contrast, naloxone (1.0–10 mg/kg) plusd-amphetamine attenuated the graded increase in response rates produced byd-amphetamine. Naloxone (1.0–10 mg/kg) plus phencyclidine did not reliably change the increase in response rates produced by phencyclidine alone. The use of the fixed interval schedule of brain self-stimulation to study these drug interactions is novel, and further demonstrates that the highly reinforcing aspects of brain stimulation, known to be influenced by dopamine, may also be modulated by the endogenous opiate system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245931
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  • 6
    Electronic Resource
    Electronic Resource
    Local alteration of cortical actin in Xenopus eggs by the fertilizing sperm (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 35 (1993), S. 69-75 
    Details
    ISSN: 1040-452X
    Keywords: Amphibian ; Microfilaments ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rhodamine phalloidin (Rph) staining was used to examine the microfilament organization of the Xenopus laevis egg cortex during the early stages of fertilization. Unactivated eggs possessed a cytochalasin B (CR)-insensitive Rph-stained matrix that was reorganized upon egg activation and diminished in the presence of CB. Xenopus laevis sperm caused a temporary local increase in Rph staining on the Xenopus cortex. In CB-treated eggs, the local increases of cortical Rph staining later changed to a Rph-free area. These temporary local increases of cortical Rph staining were also observed when Notophthalmus viridescens sperm fertilized Xenopus and Rana pipiens eggs, and were followed by the appearance of concentric rings of stained and unstained areas. Our data suggest that Xenopus and Notophthalmus sperm have activities that can both organize and disrupt the cortical filamentous actin of the Xenopus egg. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080350112
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  • 7
    Electronic Resource
    Electronic Resource
    Electrochemical detection in capillary electrophoresis (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 2267-2278 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Electrochemical detection ; Decoupling ; Capillary-electrode alignment ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Recent advances in the design and application of electrochemical detection (EC) systems in capillary electrophoresis (CE) are reviewed, with the objective of providing the non-electrochemist with a state-of-the-art picture of CEEC instrumentation and an overview of the primary analytes and samples for which the technique is best suited. In particular, instrument innovations designed to aid in decoupling the CE and EC systems electrically and in aligning them physically are described in detail. In addition, CEEC applications are summarized for four specific analyte groups: catecholamines, thiols and disulfides, amino acids, and carbohydrates. On this basis, it is clear that EC techniques have reached a stage where they are already having a significant impact on CE usage in selected areas of analysis. Continued developments with respect to new electrode materials and electrode configurations promise to broaden this impact further.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150181217
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  • 8
    Electronic Resource
    Electronic Resource
    Electrochemical detection in capillary electrophoresis with dual-parallel on-capillary electrodes (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2226-2232 
    Details
    ISSN: 0173-0835
    Keywords: Electrochemical detection ; Capillary electrophoresis ; Dual-parallel electrodes ; On-capillary electrodes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A new approach for dual electrode electrochemical detection in capillary electrophoresis (CEEC) is described. In this approach, two identical capillaries, each containing an on-capillary electrode incorporated permanently onto its tip, were paired together for simultaneous sample injection and detection. This procedure permitted dual-parallel detection to be performed without the need for painstaking alignment of the electrodes with respect to one another and to the capillary outlet as is required for the off-capillary microelectrode systems usually employed in CEEC. As a result, independent detection at two electrodes held at different potentials or at two electrodes of different composition or structure could be performed simply and with wide flexibility. Fabrication of on-capillary electrodes was carried out by sputter-coating the exit end of the capillaries with a thin layer of Au or Pt. Dual electrode system performance was demonstrated by separation and analysis of phenol and catechol samples. In addition, the detection system was coupled with glucose oxidase for the selective detection of glucose.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191230
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  • 9
    Electronic Resource
    Electronic Resource
    Capillary electrophoresis and electrochemical detection of underivatized oligo- and polysaccharides with surfactant-controlled electroosmotic flow (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 319-324 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Polysaccharides ; Electrochemical detection ; Cu electrode ; Carbohydrates ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Complex polysaccharide mixtures were analyzed directly without derivatization by capillary zone electrophoresis in strongly alkaline solutions and electrochemical detection at a Cu electrode. The positively charged surfactant cetyltrimethylammonium bromide was included in the electrophoresis medium in order to reverse the electroosmotic flow and permit elution to be in order of increasing polysaccharide size. Carbohydrate samples analyzed by this approach included linear maltoses, enzymatically hydrolyzed starch, and commercially available dextrans of up to an average molecular weight of 18 300. Detection by constant-potential oxidation at a Cu electrode was very sensitive, with detection limits for individual carbohydrates generally below the femtomole level.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150170206
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