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  • 1995-1999  (27)
  • 1990-1994  (37)
  • 1955-1959  (7)
  • 1950-1954  (4)
  • 1940-1944  (19)
  • 1925-1929  (6)
  • 1
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Exchange interactions and charge transfer in the Fe2+Fe3+ pair of the mixed valence [Fe2S2(dimethylmethanebisbenzimidazolate)2]3− trianion have been studied by analysis of Mössbauer spectra in the temperature range of 1.5–180 K and in applied fields of 10 mT, 0.35 T, and 6.2 T. The low-temperature spectra reveal a ground state with total spin St=1/2 and hyperfine parameters intermediate between values for a Fe2+Fe3+ localized mixed-valence pair and a fully delocalized system where the two iron atoms are equivalent. A consistent set of hyperfine parameters has been derived by fitting the spectra with a stochastic relaxation model taking into account spin relaxation in the St=1/2 state and electron hopping between the iron ions. An interpretation of the values of the hyperfine parameters has been given by solving a spin Hamiltonian, which includes antiferromagnetic and double exchange in an asymmetric Fe2+Fe3+ pair and which allows partial electron delocalization. Using the value a2=0.8 for the delocalization coefficient and an estimate of Δ=105 cm−1 for the difference between the St=1/2 and the first excited St=3/2 state we have derived limits for the exchange-coupling constant J, the double-exchange parameter B, and the energy difference EA−EB arising from the two possible configurations FeA2+FeB3+ and FeA3+FeB2+, i.e., 70 cm−1(approximately-less-than)J(approximately-less-than)300 cm−1, 0〈||B||(approximately-less-than)395 cm−1, and 0〈||EA−EB||(approximately-less-than)590 cm−1.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Specific antisera were raised against the A and B chains of glycoprotein III. lmmunoblotting revealed that in adrenal medulla both chains migrate very closely together in two-dimensional electrophoresis. Both chains with slightly differing molecular sizes are found in several endocrine tissues and in brain, kidney, liver, and serum. The mRNA has an analogous widespread distribution. In primary cultures of chromaffin cells the level of message becomes significantly increased by treatment with hista-mine or 12-O-tetradecanoylphorbol 13-acetate/forskoIin. However, the increase is small when compared with that of secretogranin II. The subcellular localization of glycoprotein III in endocrine organs and in the posterior pituitary was investigated by subcellular fractionation and immuno-electron microscopy. Glycoprotein III was found to be confined to the large densecore vesicles of these organs. For a discussion of the function of glycoprotein III, its localization in these organelles has to be taken into account.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Secretoneurin (SN) is a neuropeptide derived from secretogranin II that is found in brain and endocrine tissues. The aim of the present study was to determine the influence of this novel peptide on dopamine (DA) release from rat striatum using the microdialysis technique. Rat SN (1–30 µmol/L added to the dialysis buffer) enhanced DA outflow of awake rats in a concentration-dependent way without marked effects on the outflow of 3,4-dihydroxyphenylacetic acid or homovanillic acid. The increase in extracellular DA content caused by the peptide was observed throughout the entire period of administration (up to 4 h). Human SN and its 15-amino-acid C-terminal sequence also increased DA outflow, but the effects were smaller than those of rat SN. Two other peptides derived from secretogranin II were without effect on DA efflux. These results establish that SN has a pronounced effect on DA release under in vivo conditions.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3272-3278 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic garnet films of composition (Y,Bi)3(Fe,Al)5O12 are grown by liquid phase epitaxy on [111] oriented substrates of Gd3Ga5O12. They support periodic lattices of parallel stripe domains. A simple strip antenna is used to excite the domain wall resonance and the two branches of the domain resonance in the frequency range up to 5 GHz. The resonance frequencies and the dynamic components of the magnetization are calculated using a hybridization model. Good agreement between calculated and measured resonance frequencies is obtained if the quality factor of the film is larger than 0.6. Optical modes are coupled into the waveguiding film. The excited domain resonances cause dynamic conversion of transverse electric and transverse magnetic modes by the Faraday and the Cotton–Mouton effects. Mode coupling and conversion are calculated by the perturbation theory. The dynamic conversion efficiencies are measured at the fundamental and the first harmonic frequency and at zero diffraction order as a function of the static induction applied in the film plane parallel to the stripes. Conversion efficiencies up to 18% are achieved at a frequency of 2.8 GHz. From the experimental data the precession angles are derived.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 44 (1990), S. 131-153 
    ISSN: 0066-4227
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In situ hybridization was used to study the mRNA levels for secretogranin II and VGF in comparison with those of oxytocin and vasopressin in the hypothalamus of rats. VGF is a widespread constituent of large dense core vesicles which is selectively induced in PC12 cells by nerve growth factor. After adrenalectomy the mRNA levels of secretogranin II, VGF and vasopressin were increased 4- to 5-fold in the parvocellular neurons of the paraventricular nuclei. In lactating rats the message for oxytocin and secretogranin II were significantly elevated in the magnocellular neurons of the paraventricular and supraoptic nuclei, whereas for VGF only a smaller non-significant increase was observed. As shown by immunoelectron microscopy secretoneurin (a peptide derived from secretogranin II) and oxytocin are co-stored in the large dense core vesicles of the hypothalamo-neurohypophysial neurons.These results demonstrate that stimulation of both parvo- and magnocellular neurons of the hypothalamus induces a concomitant increase of the messages for secretogranin II and VGF together with those of vasopressin and oxytocin.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Secretoneurin is a recently described peptide derived by endoproteolytic processing from secretogranin II, previously named chromogranin C. In this study, we have investigated the distribution of secretoneurin-like immunoreactivity in the human hippocampus in controls and in Alzheimer's disease patients, and compared the staining pattern to that of calretinin. Secretoneurin-like immunoreactivity is present throughout the hippocampal formation. At the border of the dentate molecular layer and the granule cell layer, a band of dense secretoneurin immunostaining appeared. In this part, as in the area of the CA2 sector, the high density of secretoneurin-immunoreactivity coincided with calretinin-like immunoreactivity. The mossy fibre system displayed a moderate density of secretoneurin-immunoreactivity. In the entorhinal cortex, a particularly high density of secretoneurin-immunoreactivity was observed. The density of secretoneurin-like immunoreactivity was significantly reduced in the innermost part of the molecular layer and in the outer molecular layer of the dentate gyrus in Alzheimer's disease. For calretinin-like immunoreactivity, a less pronounced decrease was found in the innermost part of the molecular layer. About 40–60% of neuritic plaques were secretoneurin-immunopositive.This study shows that secretoneurin is distinctly distributed in the human hippocampus and that significant changes of secretoneurin-like immunoreactivity occur in Alzheimer's disease, reflecting synaptic loss.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 3 (1991), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The mRNA distribution of chromogranins A and B and secretogranin II was determined in rat brain. In Northern blots the oligonucleotide probes used hybridized with single mRNA species of the expected sizes. With tissue hybridization the mRNA signals for these three proteins were found throughout the brain. However, each of the three messages had a distinct distribution, which was exemplified by the fact that in the various regions either all three proteins, a combination of two or only one of them were apparently synthesized. Significant levels of all three mRNAs were found in several regions of the hippocampus and of the amygdala, in some thalamic nuclei and in the pyriform cortex. On the other hand the subiculum contained only the message for chromogranin A, the granule cell layer of the cerebellum only that for chromogranin B, and in posterior intralaminar thalamic and medial geniculate nuclei and in the nucleus of the solitary tract only secretogranin II mRNA was found. The distinct distributions of mRNAs for the chromogranins in various brain regions support the concept that these proteins are propeptides giving rise to functionally active components.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 8 (1996), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: An antiserum was raised against the peptide PE-11 whose sequence is present in the chromogranin B molecule. The antiserum reacts only with the free C-terminal end of this peptide. PE-11 immunoreactivity in brain was characterized by molecular size exclusion high performance liquid chromatography. Only the free peptide and a N-terminally elongated peptide were detected, indicating that proteolytic processing of chromogranin B in brain is quite extensive. In immunohistochemistry PE-11 immunoreactivity was found in varicosities, fibres and perikarya throughout the brain. Strong staining was detected in the shell sector of the nucleus accumbens, in the lateral septum, in subregions of the extended amygdala, in some areas of the hippocampus and of the hypothalamus, in the locus coeruleus, in the Purkinje cells of the cerebellum and in the dorsal horn of the spinal cord. Our results, which demonstrate significant processing of chromogranin B in brain and its widespread distribution, can be taken as an indication that chromogranin B represents a precursor of peptides with functional relevance for this organ.
    Type of Medium: Electronic Resource
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