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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    LCEC of underivatized polypeptides and proteins at copper electrodes (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 393-401 
    Details
    ISSN: 1040-0397
    Keywords: Proteins ; polypeptides ; amperometric detection ; liquid chromatography ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Constant potential amperometric detection of underivatized polypeptides and proteins can be carried out at metallic copper electrodes. When coupled with liquid chromatography, this approach provides a sensitive and selective method of analysis for these compounds. Two different detection mechanisms can be employed: a neutral pH, low potential oxidation process attributed to enhanced dissolution of the electrode by peptide species capable of forming soluble Cu(II) complexes and a high pH, high potential electrocatalytic oxidation of the analytes. Of the two approaches, the latter process was found to be more attractive for LCEC applications as it was useful for a wider range of peptides and proteins and gave substantially larger currents and lower detection limits. The compounds exhibiting useful electrocatalytic response at the copper electrode ranged from oligopeptides such as enkephalins and bradykinin to very large proteins such as glucose oxidase (F.W. 160,000) and catalase (F.W. 240,000). The response was not dependent on the presence of tyrosine, tryptophan, or cysteine amino acid units and was shown to be compatible with both ion-exchange and reverse-phase separation schemes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040406
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Liquid chromatography/electrochemical detection of hydroxylamines by oxidation at a cobalt phthalocyanine chemically modified electrode (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 353-360 
    Details
    ISSN: 1040-0397
    Keywords: Hydroxylamines ; Electrocatalysis ; Liquid chromatography ; Modified electrodes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemically modified electrodes (CMEs) containing a polymeric cosating of cobalt phthalocyanine (CoPC) were shown to catalyze the electrooxidation of hydroxylamine (NH2OH) and its N-mono-, N,N-di-, and O-substituted derivatives. All of these compounds were oxidized at unmodified glassy carbon electrodes only at potentials higher than +1 V (vs. Ag/AgCl) but gave substantial anodic currents between +0.25 and +0.55 V at the CoPC-coniaining surface. On the basis of exhaustive electrolysis experiments, the number of electrons transferred for the oxidations was found to vary between 1.2 and 1.6 depending on the particular hydroxylamine compound and the specific condition, of the electrolysis; and the products included oximes, azoxy compounds, and dimeric species. These observations were consistent with an electrocatalytic mechanism involving oxidation of the hydroxylamine by electrogenerated Co(III)PC and subsequent reaction of the initially formed oxidatior products by several pathways. When the CoPC CME was used as the sensor in amperometric detection following liquid chromatography, the detection limits obtained at +0.55 V ranged from 0.4 pmol for hydroxylamine itself up to 40 pmol for N,O-dimethylhydroxylamine. By maintaining the applied potential at +0.20 V, the detection could be made selective for hydroxylamine and N-mono-substituted hydroxylamine compounds only.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060502
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  • 5
    Electronic Resource
    Electronic Resource
    Liquid chromatography and electrochemical detection of organic peroxides by reduction at an iron phthalocyanine chemically modified electrode (1993)
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 547-554 
    Details
    ISSN: 1040-0397
    Keywords: Organic peroxides ; Detection for liquid chromatography ; Modified electrodes ; Electrocatalysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemically modified carbon paste electrodes containing incorporated iron phthalocyanine (FePC) exhibited an electrocatalytic response for the reduction of organic peroxides. In pH 2 phosphate buffer, reduction at the FePC chemically modified electrode (CME) occurred at +0.1 to +0.2 V (vs. Ag/AgCl) for all peroxides examined except for dialkyl compounds. Because this potential was 100 mV more positive than that required for oxygen reduction at this electrode, amperometric detection of peroxides by this approach was possible in flow injection and high-performance liquid chromatography without deoxygenating the sample or mobile phase solutions. In flow injection, the detection limit using this approach was 5 picomole (pmol) for hydrogen peroxide and varied from less than 1 pmol to as high as several hundred pmol for other peroxides. Cyclic voltammetry (CV) and visible spectroscopy experiments were consistent with a two-step electrocatalytic mechanism involving the Fe(III)PC/Fe(II)PC couple.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140050704
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  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of electrodes coated with metal hexacyanoferrate as amperometric sensors for nonelectroactive cations in flow systems (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 263-271 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two electrodes modified with either nickel or cupric hexacyanoferrate films were evaluated and compared as sensors for nonelectroactive cations in a flow-injection system. Both gave responses for group 1A and ammonium ions, but only the electrode modified with cupric hexacyanoferrate was sufficiently stable for use in flowing solutions. This electrode responded to K+, NH4+, Rb+, and Cs+ ions rather selectively. Within this group, the selectivity could be controlled from general to almost specific toward Cs+ by the potential at which the electrode was poised. The electrode was compatible with a mobile phase of dilute nitric acid commonly used in ion chromatography, and chromatographic detection limits of 2 × 10-7 M and linear responses over two decades were obtained. The electrode was applied to the ion chromatographic analysis of K+ and NH4+ in urine and K+ in blood serum samples.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140020402
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  • 7
    Electronic Resource
    Electronic Resource
    Electrocatalytic amperometric detection at polymeric cobalt phthalocyanine electrodes (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 119-124 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glassy carbon electrodes modified with a coating of a cobalt phthalocyanine containing polymer offer attractive features for applications as electrocatalytic amperometric sensors following liquid chromatography. These electrodes, which are formed by the anodic electropolymerization of Co-4,4′,4″,4‴-tetraaminophthalocyanine, exhibit electrocatalytic properties similar to those of earlier carbon paste electrodes containing Co phthalocyanine monomer added directly to the paste mixture. However, the polymer electrodes also offer increased stability and a compatibility with organic solvents not obtainable with the carbon paste version. The performance of the polymer electrodes is illustrated here for the detection of thiols following reversed-phase liquid chromatography. Determination of picomole quantities of various thiols is possible at low positive potentials in mobile phases composed of 50% methanol or acetonitrile. Furthermore, the response of the electrodes is extremely stable, with more than 80% of the initial activity retained after 40 hours of continuous use.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030208
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  • 8
    Electronic Resource
    Electronic Resource
    Determination of 2-thiothiazolidine-4-carboxylic acid in urine by liquid chromatography with electrochemical detection (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 515-519 
    Details
    ISSN: 1040-0397
    Keywords: Ampeerometric detection ; 2-thiothiazolidine-4-carboxylic acid ; modified electrode ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An assay procedure utilizing liquid chromatography and amperometric detection at a chemically modified electrode (CME) has been developed for the determination of 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine samples. The electrocatalytic activity of the CME, which consisted of a glassy carbon surface coated with an electropolymerized cobalt phthalocyanine film, permitted optimum response at a potential of +0.75 V vs. Ag/AgCl with a detection limit of 7 pmol for TTCA and with no sample preparation required. In case of fouling of the electrode surface by sample constituents, the polymeric cobalt phthalocyanine electrode surface could be renewed with a variability of less than 10% and an equilibration time of less than 15 minutes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040420
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  • 9
    Electronic Resource
    Electronic Resource
    Electrochemical characterization of aminated PVC-based ion-selective membranesDedicated to the memory of Prof. Wilhelm Simon. (1993)
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 725-730 
    Details
    ISSN: 1040-0397
    Keywords: Ion selective electrodes ; pH sensors ; aminated PVC ; impedance measurements ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potentiometric and impedance characteristics of a large number of pH sensitive, piperazine-based aminated PVC membranes are summarized. The main goal of the work was to predict the differences between “good” and “bad” responsive potentiometric pH membranes with very similar overall nitrogen contents. The only conclusion gained previously from other methods was that the N content should be between 0.5 and 0.8% for Nernstian response. The detailed analysis of the data show that a given N content of the basic material is a necessary but not a sufficient requirement with respect of the quality of potentiometric response. Conditions for appropriate pH response of the membrane are formulated in terms of surface and bulk impedance characteristics. The ideal pH response of an optimized aminated PVC membrane, which corresponds to a minimum surface impedance, is presented. The primary importance of surface amines relative to bulk amines (the conformation and distribution of active sites) is proven in a simple experiment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140050904
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