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  • Chemistry  (15)
  • Life and Medical Sciences  (12)
  • L-type Ca2+ channels  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Effects of nimodipine and/or haloperidol on the expression of conditioned locomotion and sensitization to cocaine in rats (1994)
    Springer
    Psychopharmacology 114 (1994), S. 315-320 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Nimodipine ; Haloperidol ; L-type Ca2+ channels ; Dopamine receptors ; Behavioral sensitization ; Conditioned locomotion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The development of classical conditioning of cocaine's locomotor effects can be dissociated from the development of sensitization to cocaine by co-administration of haloperidol, a dopamine D2-like receptor antagonist, and nimodipine, an L-type calcium channel antagonist. The effects of these agents on theexpression of conditioning and sensitization are described in the present report. Rats were given injections of vehicle or cocaine (10 mg/kg, IP) for 10 days before placement in a specific context in which locomotor activity was recorded. Neither haloperidol (0.05 mg/kg, IP) nor nimodipine (10 mg/kg, SC) influenced the expression of classical conditioning of cocaine's locomotor effects to the situational context on a subsequent cocaine-free test. Combined treatment of rats with both drugs did block classical conditioning with cocaine. Nimodipine, but not haloperidol, blocked the expression of behavioural sensitization to cocaine after a cocaine challenge. It is concluded that the expression of cocaine-induced classical conditioning can be pharmacologically dissociated from the expression of behavioural sensitization to cocaine. Furthermore, the effects of nimodipine and haloperidol on the expression of conditioning and sensitization are different from their effects on the development of these phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244854
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  • 2
    Electronic Resource
    Electronic Resource
    Unbiased cocaine conditioned place preferences (CPP) obscures conditioned locomotion, and nimodipine blockade of cocaine CPP is due to conditioned place aversions (1997)
    Springer
    Psychopharmacology 130 (1997), S. 327-333 
    Details
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Stimulants ; Nimodipine ; L-type Ca2+ channels ; Locomotor activity ; Conditioned place preferences ; Conditioned place aversions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of nimodipine (0, 0.1, 1.0 and 10 mg/kg, SC), a dihydropyridine L-type Ca2+ channel antagonist, on the establishment of cocaine-(10 mg/kg IP) conditioned place preferences (CPP) was investigated. Nimodipine produced conditioned place aversions (CPA) on its own; reductions in cocaine CPP are apparently due to this CPA. There is a high negative correlation between time spent in the CS+ compartment and the difference in locomotion rates between the CS+ and the non-drug (CS−) compartments, independent of drug effects. This relationship is responsible for an increased rate of locomotion observed in the CS− compartment in cocaine-conditioned rats. Analysis of covariance indicated that cocaine CPP occurred independently of cocaine’s effects on locomotion. Furthermore, cocaine produces an increase in the rate of locomotion in the CS+ compartment when time spent in this compartment is equated with time spent in the CS− compartment. This suggests that cocaine’s effects on CPP and “conditioned” locomotion are due to separate mechanisms of action. On the other hand, nimodipine-induced place aversions and locomotor rates are not independent of each other, indicating a common mechanism of action, or that one is a consequence of the other. It is concluded that place preferences and place aversions can sometimes be secondary to compartment-specific locomotor changes, and locomotion effects can be confounded by differential times spent in each compartment. The relationships between these two behaviours must be controlled for before conclusions of CPP or CPA can be drawn in drug conditioning studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050247
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  • 3
    Electronic Resource
    Electronic Resource
    Nimodipine and haloperidol attenuate behavioural sensitization to cocaine but only nimodipine blocks the establishment of conditioned locomotion induced by cocaine (1994)
    Springer
    Psychopharmacology 113 (1994), S. 404-410 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Nimodipine ; Haloperidol ; L-type Ca2+ channels ; Behavioral sensitization ; Classical conditioning ; Conditioned locomotion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The classical conditioning of the behavioural effects of cocaine has been shown to contribute to behavioural sensitization. In the present experiments, it was demonstrated that the effects of cocaine in rats can be conditioned to contextual stimuli. Furthermore, sensitization to cocaine's locomotor effects were demonstrated, and shown to be context specific. Nimodipine (10 mg/kg, SC), an L-type dihydropyridine Ca2+ channel antagonist, appeared to completely block the establishment of conditioning of cocaine's effects, but only partially blocked sensitization to cocaine. Haloperidol (0.05 mg/kg, IP), a relatively specific D2 dopamine receptor antagonist, attenuated behavioral sensitization but had no influence on the establishment of the conditioned component of cocaine. These results indicate that the sensitization to, and the development of classical conditioning of, cocaine's behavioural effects can be pharmacologically dissociated, but that a non-associative process involved in sensitization is normally overridden by conditioning factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245216
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular weight distribution in a polymer film degraded by lightProd. No. 1261 (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 353-359 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An explicit expression is derived for the weight distribution function of polymer molecules in a photodegraded film. A most probable weight distribution of linear molecules is assumed initially present; normally incident, monochromatic light obeying a single Beer-Lambert absorption relation is the photolyzing radiation. The dependence of the weight distribution upon the film's optical thickness and the integrated incident light flux is illustrated by curves computed according to the derived functions. Predicted gel permeation chromatograms are indicated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1966.070100301
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of trypan blue on the serum proteins of the fetal ratSupported by research grant AM-05603-03 from the National Institute of Metabolic Diseases, Public Health Service, U. S. Department of health, Education, and Welfare. (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 147 (1963), S. 387-395 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Pregnant rats were injected intraperitoneally with a teratogenic dose of trypan blue (14 mg/100 g or 20 mg/100 g body weight) on the eighth day of gestation. Fetal blood was collected from control and experimental fetuses on the twentieth day of pregnancy. Serum was obtained from pooled blood samples of two to three fetuses. Paper electrophoresis was carried out in a Spinco model R system using barbital buffer at pH 8.6. The paper strips were subsequently stained with bromphenol blue and their density measured in a Spinco Analytrol to determine the relative concentration of each component. Total protein was measured in a Bausch and Lomb Serum Protein Meter. The predominant malformations seen in abnormal fetuses were apparent anophthalmia, 59%; hydrocephalus, 37%; and exencephaly, 19%. Other malformations were noted but with less frequency. Twenty-day fetuses from trypan blue treated mothers had a significantly lower total protein concentration (1.50 g/100 ml) than control fetuses (1.95 g/100 ml). A comparison of the absolute protein concentration of the serum fractions revealed significant differences between control and experimental fetuses in beta globulin, alpha-1 globulin, and albumin. In each instance the absolute concentration was less in the fraction from fetuses of trypan blue treated mothers. Fetal gamma, alpha-2, and alpha-3 globulins were not affected by the maternal treatment.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091470310
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  • 6
    Electronic Resource
    Electronic Resource
    Surface coat material associated with the developing otic placode/vesicle in the chick (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 220 (1988), S. 198-207 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Surface coat material (SCM) has been illustrated in association with the apical surfaces of numerous epithelia during morphogenesis. This study investigates the development of a SCM associated with the invaginating otic placode/vesicle in the chick. Glycoconjugate containing SCM was retained by the inclusion of cetylpyridinium chloride (CPC) in the fixative, histochemically visualized by using ruthenium red (RR) staining, and viewed by scanning (SEM) or transmission (TEM) electron microscopy. Initial characterization of the glycoconjugates present in this material was elucidated by using lectins conjugated to fluorescein isothiocyanate. Lectins utilized included concanavalin A (Con A), wheat germ agglutinin (WGA), and soybean agglutinin (SBA). Invagination of the otic placode was apparent as early as stage 12. By stage 15 the vesicle was beginning to separate from the surface ectoderm as evidenced by its aperture, which was altered in shape and reduced in size. All embryos fixed with glutaraldehyde containing either CPC or RR were shown to possess SCM associated with the surface ectoderm, particularly in the area of the otic placode/vesicle. Additional embryos were processed by cryofixation without prior alehyde fixation; these also exhibited SCM. All lectins labelled the epithelium of the otic placode/vesicle. However, their binding patterns were not identical. The binding of Con A and WGA remained constant over the stages studied, while SBA increased as the otic vesicle developed. The data clearly indicate that otic placode morphogenesis is accompanied by the synthesis of SCM rich in glycoconjugates.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092200211
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  • 7
    Electronic Resource
    Electronic Resource
    Multiple glycoproteins localize to a particulate form of extracellular matrix in regions of the embryonic heart where endothelial cells transform into mesenchyme (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 232 (1992), S. 285-292 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cells derived from an epithelial-mesenchymal transformation within the atrioventricular canal and outflow tract are involved in the partitioning of the early embryonic heart into a four-chambered organ. This transformation process has been shown to proceed from an inductive interaction between the myocardium and competent, target endothelial cells within these regions of the heart. Interestingly, immunohistochemistry revealed the presence of fibronectinpositive particulates within the matrix of mesenchyme-forming regions (Mjaatvedt et al., 1987). This particulate matrix is extractable by EDTA and can elicit the epithelial-mesenchymal transformation in culture (Mjaatvedt and Markwald, 1989). Analysis of EDTA extracts of embryonic heart tissue revealed the presence of fibronectin and about 40 unidentified proteins, 6 of which appeared to be enriched in the biologically active 100,000g pellet fraction (Mjaatvedt and Markwald, 1989). Based on these and other data we have proposed that the particulate matrix is composed of a multicomponent complex of fibronectin and one or more of the low-molecular-weight proteins in this pellet. The purpose of the present study was to begin a biochemical characterization of the nonfibronectin proteins thought to be present in the matrix particulates. Given that many matrix constituents are glycoproteins, lectins were used to initially characterize the particulate constituents. Of the lectins tested, soybean agglutinin (SBA) was found to be specific only for matrix particulates. Histochemical analyses showed that SBA and antibodies against fibronectin colocalized regionally and temporally to the same matrix particulates in embryonic heart tissue. SBA-agarose affinity chromatography resulted in the isolation of two major (56 and 69 kDa) and six minor (28, 46, 50, 53, 126, 220 kDa) proteins from EDTA extractable heart matrix. Temporal lectin histochemical studies indicate that SBA-positive particulates are present in the matrix prior to mesenchyme formation, but are absent shortly after the transformation event. These observations support our hypothesis that one or more of these SBA-positive glycoproteins participate in the endothelial-mesenchymal transformation of cardiac endothelium.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092320213
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular weight characterization of soluble high performance polyimides. 1. Polymer-solvent-stationary phase interactions in size exclusion chromatography (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1429-1439 
    Details
    ISSN: 0887-6266
    Keywords: soluble aromatic polyimides ; size exclusion chromatography ; molecular weight characterization ; mobile phase/stationary phase interactions (SEC) ; high performance polyimides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Soluble, fully cyclized m-amino phenyl acetylene terminated polyimides based on several anhydride/diamine monomers were prepared in N-methylpyrrolidine (NMP) and cyclized by solution imidization to controlled molecular weight. The polyimides and a polyamic acid precursor were successfully analyzed by size exclusion chromatography (SEC) utilizing online parallel coupled refractive index and differential viscometer detectors. The calculated Mnvalues were varied from 3,000 to 20,000 daltons. N-methylpyrrolidone (NMP), tetrahydrofuran (THF), and chloroform served as mobile phases for the cross-linked polystyrene gel packings. Normal retention behavior of the polyimides was observed in chloroform, THF, and NMP containing LiBr, or in NMP stirred over P2O5 before use. Values of Mark-Houwink-Sakurada exponents for narrow distribution linear polystyrene indicate that pure NMP and NMP with 0.06 M LiBr are good solvents for polystyrene standards at 60°C. In contrast, SEC behavior of polyimides in pure NMP leads to splitting of the peaks with the major portion observed to pass through the columns at the exclusion limit. In contrast to strong polymeric chain expansion of the polyamic acid in dilute solution, presumably due to a polyelectrolyte effect, no increase of intrinsic viscosity of polyimide samples in pure NMP was observed. This exclusion effect of polyimides analyzed in NMP is discussed in terms of possible ion-exclusion from pores of the stationary phase. Differences in polystyrene calibration in NMP with or without additives and the temperature dependence of calibration curves in these mobile phases is discussed as well. ©1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331001
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  • 9
    Electronic Resource
    Electronic Resource
    Radiolysis of polymethyl isopropenyl ketone (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 47 (1960), S. 267-276 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymethyl isopropenyl ketone (PMIPK) undergoes random chain scission when irradiated at 23°C. with gamma rays or with ultraviolet light. Total energy absorption per chain scission, Ed, is 94 e.v./scission for PMIPK powders irradiated in vacuo with spent reactor fuel element gamma rays (0.42 Mrad/hr.). Ed is 84 e.v./scission for a PMIPK powder irradiated in vacuo with Co60 gamma rays (0.109 Mrad/hr.). The presence of air lowers the value of Ed to 41 e.v./scission under the former conditions. A film of PMIPK irradiated in air with 2537-A. wavelength light exhibits Ed = 22 e.v./scission or a quantum yield φd = 0.22 chain scissions/absorbed photon. The viscosity-average molecular weights of this film vary with light exposure in accordance with theoretical predictions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204714924
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  • 10
    Electronic Resource
    Electronic Resource
    Electron irradiation of polyacrylatesContribution No. 108 from the Central Research Department, Minnesota Mining and Manufacturing Co. Presented before the Symposium on the Effect of Radiation on Polymers, Division of Polymer Chemistry, 127th Meeting of the American Chemical Society, Cincinnati, Ohio, April 5, 1955. (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 22 (1956), S. 485-494 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crosslinking and degradation of seven polyacrylates by 1000 kvp. electrons has been investigated. Gel content-radiation dose analysis reveals the energy dissipation per main-chain fracture, Ed, to be the same (530 ± 100 electron volts) for methyl, n-butyl, sec-butyl, isobutyl, and tert-butyl acrylate polymers. The energy dissipation per crosslinked unit formation, Ec, is 80-90 e.v. for methyl, n-butyl, isobutyl and neopentyl acrylate polymers. Ec may be slightly higher for poly-sec-butyl acrylate. Poly-tert-butyl acrylate possesses a uniquely high Ec of 300 e.v. The presence of hydrogen atoms alpha to the alcoholic oxygen of the ester group is believed to contribute strongly to the crosslinking reactions of polyacrylates under ionizing radiations. Poly-1,1-dihydroperfluorobutyl acrylate exhibits an initial Ec of ∼45 e.v. and an Ed of ∼450 e.v. Beyond 15 megareps the ration of main-chain fracture to crosslink formation increases.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.1202210214
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