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  • 1
    ISSN: 1435-1536
    Keywords: Molecular complex ; cationic surfactant ; phenolic derivative ; viscoelasticity ; rod-like micelle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract It was established that many crystalline molecular complexes composed of cationic surfactants such as CTAB and several phenolic derivatives were obtained from an appropriate concentrated solution system in which a remarkable viscoelasticity was developed. It is revealed that the molecular complexes have an unambiguous composition of 1:1 molar ratio of surfactants to phenolic additives. The molecular complexes also showed characteristic endothermicity of a degree that suggests the specimens to be single and a pure species. However, through repeated runs the thermal stability of the complexes seemed to be rather poor, as exhibited by a profile change in thermograms of DSC.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 270 (1992), S. 785-793 
    ISSN: 1435-1536
    Keywords: Colloids ; long-range interactions ; soft systems ; equilibrium structure ; Ornstein-Zernike equation ; HMSA closure ; statistical thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The structure of strongly interacting, charged dispersions is examined using the Ornstein-Zernike integral-equation formalism with thermodynamic consistency conditions (i.e., with the so-called HMSA closure conditions). It is shown that for highly charged dispersions interacting through screened Coulombic (Yukawa) interactions this integral-equation approach predicts the static structure factorS(q) in excellent agreement with Monte Carlo results and that it is better than the rescaled mean-spherical approximation. The Sogaimi potential (which predicts Coulombic attraction under identical physicochemical conditions) is also considered here as a model potential for representing soft, long-ranged interactions with an attractive component. None of the integralequation formalisms, including the HMSA theory and the reference hypernetted-chain (RHNC) theory, leads to a sufficient level of thermodynamic consistency for the latter potential, and the results deviate noticeably from the Monte Carlo results. We further demonstrate that fitting the experimentally observed structure factors in the neighborhood and beyond the primary peak inS(q) could lead to inaccurate conclusions concerning the nature of interparticle forces, particularly in the case of soft, long-range interactions.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1536
    Keywords: N-octanoyl-L-glutamic acid oligomers ; phase structure ; β-structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract N-Octanoyl-L-glutamic acid oligomer benzyl esters (residue number,N=1–4, 6, 8, and 12) have been synthesized. For the solid samples ofN=3–12, x-ray powder diffraction pattern and vibrational spectroscopic measurements have led to the assumption of a β-sheet structure. For the CHCl3-solutions of theN-octanoyl tetramers, hexamers, and octamers, the phase diagram consists of three regions (I, II, and III). Region I is an isotropic phase, in which the aggregate structure strongly depends upon concentration, and region II is a lyotropic liquid crystal area. Region III is a two-phase area in which regions I and II coexist. In the case of the trimer solutions, it consists of two regions (I and II). For the oligomers withN=3–12 in region I, it was assumed that micellization induces preferential stabilization of the β-sheet structure depending on the concentration. Further stabilization of the β-sheet structure, was found to occur in region II. For the hexamer, octamer, and dodecamer in CHCl3, results from light-scattering measurements have led to an estimate of the apparent weight-average molecular weights and aggregation numbers of the micelle in region I.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1890
    Keywords: Andosol ; Legumes ; Mineral nutrition Plant growth ; VAM fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth and mineral nutrition responses were evaluated of three tropical legumes, cowpea (Vigna unguiculata L. cv Kuromame), pigeonpea [Cajanus cajan L. (Millsp.) cv ICPL 86009] and groundnut (Arachis hypogaea cv Nakateyutaka) inoculated with two different species of VAM fungi, Glomus sp. (Glomus etunicatum-like species) and Gigaspora margarita, and grown in Andosols with different fertilities [Bray II-P: topsoil (72 ppm), subsoil (〈0.1 ppm)]. Percent fungal root colonization was high in cowpea and groundnut but relatively low in pigeonpea in both soil types. Despite the low rate of root infection, significant growth responses were produced, especially in the inoculated pigeonpea plant. In all legumes, shoot dry matter production was favoured by the inoculations. Increases in shoot biomass due to mycorrhizae were greater in the subsoil than in the topsoil. Mycorrhization raised shoot concentrations of P and Ca (in cowpea and groundnut) and P and K (in pigeonpea) in the topsoil. Whereas the P concentration in shoots in the subsoil was not positively affected by VAM fungi, particularly in cowpea and pigeonpea, the concentration of K in such plants was significantly increased by VAM treatment. The results also showed that mycorrhizal enhancement of shoot micronutrient concentrations was very rare in all plants, with negative effects observed in certain cases. Cu concentration, in particular, was not affected by VAM formation in any of the plants, and Mn and Fe in pigeonpea and groundnut, respectively, remained the same whether plants were mycorrhizal or not. In both soils the three legumes responded to Glomus sp. better than to Gigaspora margarita, and the effects of the VAM fungi on each of the crops relative to the controls were greater in the subsoil than in the topsoil. However, shoot growth of groundnut was not affected as much as cowpea and pigeonpea by the type of soil used. In spite of the relatively low infection of its root, pigeonpea was generally the most responsive of the three legume species in terms of mycorrhizal/nonmycorrhizal ratios.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1463
    Keywords: c-fos ; messenger RNA ; levodopa ; carbachol ; trihexyphenidyl ; interaction ; modulation ; striatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To clarify the interactions between dopamine receptors and muscarinic cholinergic receptors by which neurotransmitters may affect genetic responses, we studied the effects of the muscarinic cholinergic agonist, carbachol, and the muscarinic cholinergic antagonist, trihexyphenidyl, on levodopa-induced c-fos messenger RNA (mRNA) expression in rat striatum. Animals were administered levodopa (levodopa with one-tenth dosage of carbidopa), carbachol or thrihexyphenidyl alone or administered in combination as levodopa (100 mg/kg) + carbachol, or levodopa + trihexyphenidyl given as a single bolus. Levodopa given alone increase the expression of c-fos mRNA. Although carbachol or trihexyphenidyl alone was ineffective in inducing c-fos mRNA, the combination of levodopa and carbachol (⩾ 0.1 mg/kg) significantly suppressed the induction of c-fos mRNA as compared with levodopa given alone. The combined administration of levodopa and trihexyphenidyl showed a trend toward an additive effect on the induction of c-fos mRNA vs levodopa alone. These findings suggest that the muscarinic cholinergic system may modulate the levodopa-induced c-fos mRNA expression which then regulates the expression of other mRNAs.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1463
    Keywords: Bifemelane hydrochloride ; idebenone ; indeloxazine hydrochloride ; ischemic gerbils ; monoamines and their metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bifemelane hydrochloride (bifemelane), idebenone and indeloxazine hydrochloride (indeloxazine) are used clinically to reduce apathy and other emotional disturbances in patients with cerebrovascular disease. In gerbil brains, ischemia affects many monoaminergic neurotransmitters and their metabolites. In the present study, the effects of treatment with bifemelane, idebenone and indeloxazine on ischemia-induced changes in monoamines and their metabolites were studied in ischemi gerbil brains. Although these drugs had no effect on the monoaminergic neurotransmitters or their metabolites in sham-operated animals, in the ischemi brains both dopamine and serotonin turnovers were abnormal after idebenone or indeloxazine treatment. Bifemelane, in contrast, tended to correct the ischemia-induced changes in the dopaminergic and serotonergic systems in the cerebral cortex, hippocampus and thalamus + midbrain. From the present results and those in previous reports, we conclude that bifemelane is more appropriate than idebenone or indeloxazine as a treatment for the ischemia-induced changes in monoaminergic neurotransmitter systems.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-6903
    Keywords: N-methyl-d-aspartate (NMDA) receptor ; ischemia ; neuronal death ; time course of changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Althoughneuronal death following brain ischemia was originally considered to be due to an energy deficiency resulting from an impaired respiratory chain, the observation of “delayed neuronal death” indicated some other factor. It is believed that delayed neuronal death after transient forebrain ischemia appears as a result of release of glutamate, an excitatory amino acid. In the present study, transient ischemia for 20 minutes in a rat four-vessel occlusion model was induced, and serial changes in histology and N-methyl-d-asparate receptor (NMDA-R) binding were evaluated up to the chronic stage. Destruction of pyramidal cells and extensive astrocytic proliferation in the CA1 area of the hippocampus was completed by 10 days after cerebral ischemia followed by cerebral blood recirculation. However, the glutamate receptor subtype, NMDA-R, showed no change in all brain regions until after 10 days, but decreased in the hippocampus to 50% after 21 days despite no evidence of histological progression of neuronal death. The results show that the time course for appearance of light microscopic damage in the hippocampal region does not parallel that for depletion of NMDA-R binding sites.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-6903
    Keywords: beta-2 adrenergic receptor ; in situ hybridization histochemistry ; receptor up-regulation ; reserpine ; rat brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied the distribution of the rat brain beta-2 adrenergic receptor (AR) mRNA, and the effects of monoamine depletions by chronic reserpine treatment using in situ hybridization histochemistry. In the control group, high level signals of beta-2 AR mRNA were observed in the parietal, frontal and piriform cortices, the medial septal nuclei, the olfactory tubercle, and the midbrain. Moderate signals were found in the striatum, the retrosplenial cortex, the hippocampus, and the thalamic nuclei. After chronic reserpine treatment, beta-2 AR mRNA levels were increased in many brain regions. The large increases were seen in the hippocampus, all thalamic nuclei, the amygdaloid nuclei, and the midbrain, followed by the striatum and the occipital cortex. The receptor up-regulation resulting from chronic monoamine depletion may be due to these increases in beta-2 AR mRNA, indicating that this up-regulation may be caused by increased receptor production rather than decreased receptor degradation.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1435-1463
    Keywords: c-fos ; messenger RNA ; handling ; repeated administration ; saline ; frontal cortex ; striatum ; rat brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The rough handling with repeated saline administration (1.2 ml/kg s.c. for 7 days) enhanced cortical c-fos mRNA expression in the rat brain after a single saline stimulation (1.2 ml/kg s.c.) due to increasing baseline c-fos mRNA levels, whereas the gentle handling with repeated saline administration declined c-fos mRNA expression after a single injection due to decreasing the baseline of c-fos mRNA levels. These two types of handling with the repeated injection led to diametrically opposite results on c-fos mRNA expression after a single stimulation. Neither two types of handling with repeated saline injections affected the net increment of c-fos mRNA induction after a single stimulation, therefore, the effects of handling with repeated treatment on c-fos mRNA expression might be independent of the effects of a single saline stimulation. The present study suggests that c-fos mRNA induction after a single stimulation might be affected by the types or intensities of handling and that care must be taken to estimate c-fos mRNA induction.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1435-1463
    Keywords: Neuropeptide ; serotonin depletion ; 5,7-dihydroxytryptamine (5,7-DHT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The levels of five neuropeptides (substance-P, somatostatin, cholecystokinin octapeptide, methionin-enkephalin and dynorphin) were examined in the brain and the spinal cord of rats 2 weeks after intracerebroventricular injection of 5,7-dihydroxytryptamine (5,7-DHT). 5,7-DHT injection caused a significant reduction of the serotonin level in all regions of the brain. The level of each neuropeptide except dynorphin significantly increased in specific regions of the brain after 5,7-DHT treatment without any decrease in their levels in any region. Since, coexistence and interaction between classical neurotransmitters and neuropeptides in the same neurons have been reported, both are indispensable for evaluating pathophysiological state of the brain function associated with abnormal neural transmission. The present findings together with previous reports suggest that neuropeptides act as neurotransmitters and compensate for the impaired function of the serotonergic systems.
    Type of Medium: Electronic Resource
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