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  • Analytical Chemistry and Spectroscopy  (17)
  • Amphibian  (3)
  • Morphine  (3)
  • 1
    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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  • 2
    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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    Paper (German National Licenses)
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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Capillary gas chromatography/mass spectrometry of cholesteryl esters with negative ammonia chemical ionization (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 131-140 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of both synthetic and naturally occurring (human plasma) cholesteryl esters have been examined by capillary gas chromatography/mass spectrometry (GC/MS). A magnetic sector mass spectrometer was used and a variety of ionization modes were assessed with a view to obtaining structural information on intact cholesteryl esters. By employing ammonia as reagent gas, with negative ion scanning, spectra were produced from which the nature of steryl and fatty acyl moieties could be readily deduced. Analyses were performed at an ion source temperature of 300°C in order to maintain the integrity of the gas chromatographic profile. The technique described is of general use for the GC/MS analysis of steryl esters, particularly in conjunction with magnetic sector instruments.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200140307
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  • 7
    Electronic Resource
    Electronic Resource
    Application of electrospray ionization mass spectrometry with maximum-entropy analysis to allelic ‘fingerprinting’ of major urinary proteins (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 882-886 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Mixtures of a specific group of proteins, the major urinary proteins (MUPs), believed to have a role in odorant binding, have been analysed by electrospray ionization mass spectrometry. The data obtained from conventional transformed electrospray data confirm that the molecular weights of the protein mixtures, deduced from published sequences, lie in the molecular weight range 18600 to 19 000 Da. Application of maximum-entropy analysis to the raw electrospray data has confirmed a heterogeneity in MUP composition, consistent with allelic similarities (and differences) between the different mouse strains. This work demonstrates the use of maximum entropy in the assessment of protein content and in the subsequent resolution enhancement of naturally occurring protein mixtures containing components of closely similar molecular mass.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290071005
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  • 8
    Electronic Resource
    Electronic Resource
    The determination of sequence information in homologously related proteins by mass spectrometry (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 269-273 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An azurin, a small respiratory copper protein from the bacterium Pseudomonas fluorescens biotype G, has been studied by mass spectrometry to determine sequence information. The study of homologously related proteins by mass spectiometry is particularly attractive, since the correct nature of major parts of the deduced sequences can be confirmed by comparison with the sequences of the protein from related organisms. An oxidized tryptohan residue has been identified amongst the products from a cyanogen bromide digest of this wild type azurin. In the same digest, a product is also found to arise from cleavage of the peptide chain at the C-terminal side of the same tryptophan residue. These results are rationalized.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200010411
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  • 9
    Electronic Resource
    Electronic Resource
    A novel inexpensive device for the electrochemical generation of metallic emitters for field desorption (1977)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 4 (1977), S. 52-54 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Details for the construction of a novel, inexpensive device for the electrochemical generation of metallic emitters for field desorption mass spectrometry are described. Use of the device for the generation of cobalt and nickel emitters is demonstrated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200040107
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  • 10
    Electronic Resource
    Electronic Resource
    Detection of nucleotide bases in ancient seeds using gas chromatography/mass spectrometry and gas chromatography/mass spectrometry/mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 503-508 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Nucleic acid extracts from 1400-year-old radish seeds recovered from excavations at Qasr Ibrim, Upper Egypt, have been analysed by gas chromatography/mass spectrometry and gas chromatography/mass spectrometry/mass spectrometry. tert-Butyldimethyisilyl derivatives of the purine and pyrimidine bases were prepared, after treatment of the nucleic acid extracts with concentrated formic acid. Under electron ionization these derivatives yield prominent [M-57]+ ions that were found to be of value for use in analyses employing selected-ion monitoring and product-ion studies. These two techniques were used in the sensitive and selective detection of nucieotide bases in crude extracts of ancient seeds. The results obtained were supported by complementary analyses of hydrolysates of ancient nucleic acids and authentic bases by means of retention time and spectral comparisons. This work demonstrates for the first time that mass spectrometry can be used in the direct chemical examination of nucleotide bases in ancient materials. This analytical approach is currently being used to address questions regarding the possible chemical (diagenetic) changes occurring in the nucleic acids of ancient biological material.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080702
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