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  • 1
    Electronic Resource
    Electronic Resource
    Cis-(+)-8-OH-1-CH3-DPAT, (+)ALK-3, a novel stereoselective pharmacological probe for characterizing 5-HT release-controlling 5-HT1A autoreceptors (1990)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 341 (1990), S. 149-157 
    Details
    ISSN: 1432-1912
    Keywords: Cis-(+)-8-hydroxy-1-methyl-2-(di-n-propyl-amino)tetralin [(+)ALK-3] ; Stereoselective 8-OHDPAT analogue ; 5-HT1A receptor ; Rat brain in vivo 5-HT release ; Microdialysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The somatodendritic 5-HT1A autoreceptor regulating 5-HT neuronal activity is currently poorly defined pharmacologically because there are no specific antagonists, but also because potent and stereoselective agonists are scarce. Moreover, there have been few, if any, attempts to specifically investigate structure-activity relationships for agonists acting at this site. Employing brain microdialysis techniques, we have examined the effects of the enantiomers of cis-8-hydroxy-1-methyl-2-(di-n-propylamino)tetralin (ALK-3; 0.01-0.3 mg/kg s.c.), its trans-1-methyl analogue (ALK-4; 0.3 mg/kg s.c.) and the pure enantiomers of the parent compound - 8-OH-DPAT (0.3 mg/kg s.c.) — in an attempt to address stereochemical agonist structure-activity requirements of 5-HT release-controlling 5-HT1A autoreceptors in brain. The cis-1-methylated 8-OH-DPAT analogue (+)ALK-3 was comparable to the parent compound in reducing the 5-HT output from rat ventral hippocampus. In comparison, both (−)ALK-3 and the racemic rans-diastereomer to ALK-3, ALK-4, were inactive, while the two stereoisomers of 8-OH-DPAT strongly reduced 5-HT release. Pretreatment with (−)pindolol (8 mg/kg s.c.), which has high affinity for 5-HT1A radioligand binding sites, blocked the reduction of hippocampal 5-HT release induced by a submaximally effective dose of (+)ALK-3. The direct intrahippocampal administration of (+)ALK3 (10 μM) via the perfusion medium did not affect 5-HT output. In summary, the data indicate that (+)ALK-3, like 8-OH-DPAT, is a very potent 5-HT receptor agonist which inhibits terminal 5-HT release in rat hippocampus, probably via activation of somatodendritic 5-HT1A autoreceptors. However, unlike 8-OH-DPAT, (+)ALK-3 is highly stereoselective and may therefore represent a useful probe in the further characterization of 5-HT1A receptor-mediated mechanisms and function. The present study defines some of the stereochemical requirements for 5-HT1A receptor interaction, emphasizing the importance of the receptor region complementary to the C1 and C2 carbons of the 8-OH-DPAT molecule. These findings contribute to the establishment of structure-activity relationships for the cell body 5-HT1A autoreceptors and might be of value in resolving structural features that determine agonist/antagonist activity at central 5-HT1A receptors. Finally, in conjunction with our recent finding that (+)ALK-3 is a partial agonist at postsynaptic 5HT1A receptors, the present study extends previous observations suggesting that pre- and postsynaptic 5-HT1A receptor populations differ in their characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169724
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  • 2
    Electronic Resource
    Electronic Resource
    Syntheses of well-defined star-shaped poly(tetrahydrofuran) polyols by the ion-coupling method (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3403-3408 
    Details
    ISSN: 0887-624X
    Keywords: star-shaped ; poly(THF) ; ion-coupling ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The prepoly(tetrahydrofuran) [poly(THF)] capped with hydroxyl and tetrahydrothiophenium groups was prepared using tetrahydrothiophene to terminate the living cationic polymerization of THF initiated by BF3·OEt2 and epichlorohydrin (ECH) at low conversion. Well-defined star-shaped poly(THF) polyols were synthesized by an ion-coupling reaction of the prepoly(THF) with tri- or tetrafunctional benzenecarboxylates, respectively, and this process proceeded by precipitation when the solution of the prepolymer in THF was added to an aqueous solution containing an excess of the corresponding coupling reagent. GPC studies showed that all of the carboxylate groups of every coupling reagent molecule took part in the ion-coupling reaction simultanously. This was confirmed by IR spectra. Almost all of the prepolymers were coupled to form star polymers after repeating the precipitation four times. 1H-NMR illustrated that both the star-shaped polymers and the prepolymers contained primary and secondary hydroxyl end groups. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3403-3408, 1997
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Cationic polymerization of 1,3-dioxepane in the presence of 2,2-bis(hydroxymethyl)butanol (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2899-2903 
    Details
    ISSN: 0887-624X
    Keywords: cationic ring-opening polymerization ; poly(1,3-dioxepane) triol ; 2,2-bis(hydroxymethyl)butanol ; transacetalization ; activated monomer mechanism ; activated chain mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cationic polymerization of 1,3-dioxepane (DOP) initiated by triflic acid was carried out in the presence of 2,2-bis(hydroxymethyl)butanol (BHMB). The structure and molecular weight of the products were characterized by GPC and NMR spectra. The results showed that molecular weight of the polyacetal obtained could be controlled by the initial mole ratio of DOP/BHMB. GPC showed that as the mole ratio of BHMB/DOP increased, the content of cyclic oligomers also increased. Proton, 13C and 2D HMQC-fg NMR demonstrated that no hydroxymethyl group of BHMB appeared as an end group. It was also illustrated by proton NMR that some BHMB units existed in cyclic oligomers. The mechanism of formation of cyclic oligomers was discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2899-2903, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Gas permeabilities and permselectivity of photochemically crosslinked polyimides (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 485-489 
    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: Photosensitive polyimide BTDA-3MPDA was modified by UV irradiation. The structure of UV-irradiated polyimides was investigated by FTIR and gel fraction measurements. The results showed that longer UV exposure time resulted in a higher extent of crosslinking. The gas permeabilities of hydrogen, oxygen and nitrogen through UV-irradiated polyimides were characterized in a temperature range from 30°C to 90°C. Photocrosslinking resulted in a sharp decline in gas permeability for hydrogen, oxygen, and nitrogen through polyimide in the initial stage of photocrosslinking. Then, as the crosslinked benzophenone percentage amounted to 28-38% for hydrogen, 17-31% for oxygen and 3-28% for nitrogen, the gas permeabilities showed another sharp decline. Gas permselectivity increased significantly with the progress of photocrosslinking, and it can be adjusted in a wide range by controlling the extent of crosslinking. Arrhenius plots of gas permeability for hydrogen and oxygen through UV-irradiated polyimides are straight lines; for nitrogen, however, change in the slope of the straight line is observed and activation energies for hydrogen and oxygen permeation show abrupt increases when crosslinked benzophenone percentage amounts to about 30%. UV-irradiated polyimides with simultaneous high gas permeability and permselectivity make them ideal candidate materials for gas separation. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580301
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  • 5
    Electronic Resource
    Electronic Resource
    Study on the cationic polymerization mechanism of 1,3-dioxepane in the presence of ethylene glycol (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 2613-2622 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cationic polymerization of 1,3-dioxepane (DOP) initiated with trifluoromethanesulfonic acid (I) in the presence of ethylene glycol (EG) was investigated. At sufficiently low concentration of the initiator ([I] 〉 0.01 mol/L vs. [EG] 〈 0.20 mol/L), the molecular weights of the obtained polyacetal oligodiols are controlled by the mole ratio of consumed DOP to initial EG. Gel-permeation chromatography studies revealed that the concentration of cyclic oligomers in the products are negligible. The mechanism of the polymerization was investigated by means of kinetic studies. The results showed that the polymerization proceeds according to the active chain end mechanism (ACF) in combination with the activated monomer mechanism (AM); thus the cyclic oligomer in the obtained polymer is reduced, and intermolecular chain transfer to EG in ACE is dominant. It was also demonstrated that as [DOP]2[I]/[EG] decreases the contribution of ACE to the polymerization decreases and that of AM increases. In addition, 1H and 13C NMR data illustrated that each macromolecule of polyDOP oligodiols contained one EG unit on average and that no EG end groups exist.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021980819
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