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  • 1
    Digitale Medien
    Digitale Medien
    Novel Photoactivatable Agonist of the Nicotinic Acetylcholine Receptor of Potential Use for Exploring the Functional Activated State (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 67 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: The nicotinic acetylcholine receptor (AChR) exhibits at least four different conformational states varying in affinity for agonists such as acetylcholine (ACh). Photoaffinity labeling has been previously used to elucidate the topography of the AChR. However, to date, the photosensitive probes used to explore the cholinergic binding site photolabeled only closed or desensitized states of the receptor. To identify the structural modifications occurring at the ACh binding site on allosteric transition associated with receptor activation, we have investigated novel photoactivatable 4-diazocyclohexa-2,5-dienone derivatives as putative cholinergic agonists. Such compounds are fairly stable in the dark and generate highly reactive carbenic species on irradiation. In binding experiments using AChRs from Torpedo marmorata, these ligands had affinities for the ACh binding site in the micromolar range and did not interact with the noncompetitive blocker site (greater than millimolar affinity). Irreversible photoinactivation of ACh binding sites was obtained with the ligand 1b (up to 42% at 500 µM) in a protectable manner. In patch-clamp studies, 1b was shown to be a functional agonist of peripheral AChR in TE 671 cells, with the interesting property of exhibiting no or very little desensitization even at high concentrations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.67062557.x
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  • 2
    Digitale Medien
    Digitale Medien
    Whispering-gallery-mode microring laser using a conjugated polymer (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 141-143 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We observed laser emission in whispering gallery modes using a microring composed of a semiconducting polymer poly[2,5-bis-(2′-ethylhexyloxy)-p-phenylenevinylene coated on an etched fiber under transient and quasisteady-state pumping conditions. The threshold for laser oscillation was 1 mJ/cm2 (0.1 MW/cm2) and 30 μJ/cm2 (300 MW/cm2) for nanosecond and femtosecond excitation, respectively. The laser output showed superlinear dependence on the excitation energy above the threshold. The demonstration of lasing under quasisteady-state pumping shows the possibility to develop electrically pumped polymer lasers. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.120668
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  • 3
    Digitale Medien
    Digitale Medien
    Phenotypic plasticity of internode elongation stimulated by deep-seeding and ethylene in wheat seedlings (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Deep-seeding and ethylene were found to stimulate extension growth of the first internode of intact wheat (Triticum aestivum L.) seedlings in darkness. Seedlings of Hon Mang Mai emerged from much deeper in the soil than the seedlings of the other varieties used and their first internodes elongated to a much greater extent in response to ethylene. Carbon dioxide slowed elongation of the first internode and inhibited ethylene action. Elongation of the first internode due to deep-seeding and ethylene treatment showed high heritabilities, suggesting a genetic basis underlying those traits.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-126.x
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  • 4
    Digitale Medien
    Digitale Medien
    Geographical variation of β-amylase thermostability among varieties of barley (Hordeum vulgare) and β-amylase deficiency (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 118 (1999), S. 0 
    Details
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Investigations onto the thermostability of β-amylase in 274 varieties of barley (Hordeum vulgare L.) indicated that all varieties except one were distributed into three types of high (type A), intermediate (type B), and low (type C) thermostability, respectively. One variety (TB29) from China showed no β-amylase activity. Geographical variation was observed in the thermostability of β-amylase. Type C varieties were not observed in East Asia (Japan, the Korean Peninsula, China and Nepal), although 36 out of 37 varieties in Ethiopia were type C. Most of the varieties were Type A in Japan, the Korean Peninsula and China, whereas the frequency of type A and type B were nearly equal in Nepal. Varieties in the other five areas (North America, North Africa, Southwest Asia, Turkey and Europe) consisted of types A, B and C. These results support the fact that East Asian cultivars are genetically different from those of the western regions, as previously reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1439-0523.1999.00397.x
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  • 5
    Digitale Medien
    Digitale Medien
    HYPOTHALAMIC AND MEDULLARY GABAA AND GABAb-ERGIC SYSTEMS DIFFERENTLY REGULATE SYMPATHETIC AND CARDIOVASCULAR SYSTEMS (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 22 (1995), S. 0 
    Details
    ISSN: 1440-1681
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: 1. To determine whether hypothalamic and medullary GABA (gamma-aminobutyric acid)B stimulation would affect the sympathetic and cardiovascular activities, and to determine whether these effects would be altered in hypertension, baclofen (a GABAb agonist) was injected into a hypothalamic pressor area (ventromedial hypothalamus, VMH), a depressor area (anterior hypothalamus, AH), or a nucleus tractus solitarius (NTS) in normotensive and spontaneously hypertensive rats (SHR).2. Intracetebroventricular (ICV) injections of a GABAa agonist (muscimol, 1 μg) decreased blood pressure (BP) and heart rate (HR). ICV injections of baclofen (2μg) elicited biphasic depressor and pressor effects, and these effects were abolished by a pretreatment with saclofen (GABAb antagonist, 100 μg, icv).3. Muscimol (400 ng) and baclofen (800 ng) injected into VMH decreased sympathetic nerve activity (SNA), BP and HR to almost similar levels, while saclofen injected into VMH increased HR without affecting BP levels.4. The same dose of baclofen injected into AH increased BP, but muscimol (AH) did not alter BP.5. Both muscimol and baclofen injected into NTS increased BP, but its magnitude was larger in baclofen injections.6. Depressor and sympathoinhibitory effects of baclofen (VMH) in SHR were larger than those in normotensive Wistar-Kyoto (WKY) rats, while pressor responses elicited by baclofen (AH) did not differ between SHR and WKY.7. In summary, GABA reduces SNA, BP and HR through both GABAa and GABAb receptors in VMH. In addition, the GABAb system acts on AH and NTS to further regulate the cardiovascular activities. In SHR, GABAB-ergic dysfunction in VMH but not in AH might contribute to the development of hypertension.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1440-1681.1995.tb02966.x
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  • 6
    Digitale Medien
    Digitale Medien
    EFFECTS OF GAMMA-LINOLENIC AND EICOSAPENTAENOIC ACIDS ON BLOOD PRESSURE IN SHR (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 22 (1995), S. 0 
    Details
    ISSN: 1440-1681
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: 1. The present study was performed to determine whether chronic treatments with gamma linolenic acid (n-6, GLA) or eicosapentaenoic acid (n-3, EPA) would alter serum and red blood cell (RBC) unsaturated fatty acid composition, and to determine whether these treatments would affect blood pressure (BP), serum lipid metabolism and the development of atherosclerosis in spontaneously hypertensive rats (SHR).2. To compare the effects on atherosclerosis, some SHR were denuded of aortic endothelium so that the development of atherosclerosis would be accelerated. Olive oil (control), GLA or EPA (low dose: 5 mg/day per rat, high dose: 50 mg/day per kg, respectively) was administered intraperitoneally for 6 weeks in SHR.3. GLA treatments increased GLA and its metabolite, dihomo-GLA, levels in serum but not in RBC, while EPA treatments increased EPA level both in serum and in RBC.4. The BP of control SHR was further elevated. EPA significantly reduced this elevation of systolic, mean and diastolic pressure within the first week and thereafter, whereas GLA did not affect BP elevation. Neither heart rate or bodyweight gain was affected by these treatments.5. Serum total cholesterol (TC), triglyceride (TG), and glucose (G) levels and the development of atherosclerosis were unaffected by either GLA or EPA treatment.6. In summary, chronic EPA but not GLA treatment slightly reduced BP elevation in SHR. Although chronic GLA or EPA treatment increased the respective serum level, these treatments unaltered serum TC, TG and G levels, and could not prevent the development of aortic atherosclerosis in SHR.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1440-1681.1995.tb02930.x
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  • 7
    Digitale Medien
    Digitale Medien
    Comparison of basophil histamine release, eosinophil cationic protein and non-specific airway responsiveness between mite-sensitive asthmatic and non-asthmatic children and non-allergic controls (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 26 (1996), S. 0 
    Details
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: To understand the relevance of allergy to the development of asthma in children, we examined basophil hislamine release (HR) with Df antigen, blood cosinophii counts, serum eosinophil cationic protein (ECP) levels, and bronchial responsiveness to methacholine (PC20) in three groups of children, including 36 asthmatics with high RAST titre for Df (group 1), 36 non-asthmatics with similarly high RAST titre for Df (group 2) and 21 non-asthmatics with negative RAST titre for Df (group 3). The amount of Df antigen inducing 50% HR from basophils did not vary significantly between group 1 and 2 (P〉0.05), while none of the cells responded to higher concentrations of Df in group 3. The mean number of blood eosinophils and level of serum ECP were highest in group 1, and lowest in group 3, with group 2 being intermediate, and the differences were significant between all three groups (P〈0.01). The mean PC20 value was the lowest in group 1, intermediate in group 2, and the highest in group 3, and the differences were significant between all three groups (P〈0.01). While correlation studies showed that PC20 values of group 2 subjects signficantly correlated with their eosinophil numbers (r=–0.48, P〈0.01) and ECP levels (r =–0.49, P 〈 0.01), such correlations were not found in group 1 subjects. These results suggest that the degree of the eosinophilic inflammation caused by the allergic reaction to mites is an important factor in determining the clinical expression of asthma in atopic subjects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2222.1996.tb00627.x
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  • 8
    Digitale Medien
    Digitale Medien
    Synthetic surfactants for protecting cultured fish against toxic phytoplankton (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 29 (1998), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Polyoxyethylene alkyl esters, which are surface-active agents, were chemically synthesized from fatty acids (C12-C18) on reaction with different moles of polyethylene oxides, and were tested for effectiveness against the toxic raphidophytes Chattonella marina (Subrahmanyan) Hara & Chihara and C. antiqua (Hada) Ono. The synthetic surfactants destroyed cultured cells from these two species. Although the synthetic surfactants also exhibited ichthyotoxicity, this was lowered by increasing the molarity of ethylene oxide (EO) in alkyl ester molecules. Young yellowtail, Seriola quinqueradiata Temminck & Schlegel, survived exposure to C. marina (5000-5500 cells mLT−1) or C. antiqua (3000-3500 cells mL−1) cultures with the addition of 4-5 p.p.m. oleyl ester EO 14, but died within an hour without the addition of this surfactant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2109.1998.00239.x
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  • 9
    Digitale Medien
    Digitale Medien
    Calcium-sensitivity of the plasmalemmal delayed rectifier potassium current suggests that calcium influx in pulvinar protoplasts from Mimosa pudica L. can be revealed by hyperpolarization (1995)
    Springer
    The journal of membrane biology 146 (1995), S. 201-209 
    Details
    ISSN: 1432-1424
    Schlagwort(e): Mimosa pudica ; Pulvinus ; Protoplast ; Delayed rectifier potassium current ; Calcium influx ; Gadolinium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Isolated protoplasts from pulvinar motor cells of Mimosa pudica were studied using conventional whole-cell patch clamp techniques. With internal solutions weakly buffered for Ca2+ (0.2 mm EGTA), a run-down of the outward delayed rectifier K+ current was induced by hyperpolarizing the holding potential, and this effect was strongly promoted by high external Ca2+ concentrations. This rundown could be reversed by coming back to less hyperpolarized holding potentials or by lowering the external [Ca2+]. Such rundown was absent when pipette internal solutions strongly buffered (10 mm EGTA) for Ca2+ were used. Ionomycin induced run-down of the K+ current with internal solutions containing 0.2 mm but not 10 mm EGTA. The hyperpolarization-associated rundown was reversibly blocked by Gd3+ and La3+.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00238009
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  • 10
    Digitale Medien
    Digitale Medien
    The expression of Na+/K+-ATPase β-subunit cRNA injected into Xenopus oocytes is affected by coinjection with α-subunit cRNA (1995)
    Springer
    The journal of membrane biology 148 (1995), S. 51-56 
    Details
    ISSN: 1432-1424
    Schlagwort(e): Na+/K+ ; ATPase ; cDNA expression ; Subunit assembly ; Xenopus oocyte
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The cRNA for Torpedo californica Na+/K+-ATPase β-subunit (cRNAβ) was injected into Xenopus oocytes alone or with the cRNA for the Na+/K+-ATPase α-subunit (cRNAα). When cRNAβ was injected alone, the amount of the β-subunit that accumulated in oocytes increased with increasing amounts of injected cRNAβ. When cRNAβ and cRNAα were injected simultaneously, less β-subunit accumulated than when cRNAβ was injected alone, whereas the Na+/K+-ATPase activity increased markedly. The decrease in the accumulation of the β-subunit was dose-dependent upon the cRNAα. The mutant β-subunit unable to assemble with the α-subunit accumulated in oocytes independently of cRNAα, suggesting that post-translational control mechanisms may serve to reduce the accumulation of the β-subunit.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234155
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