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  • 1
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 17, No. 3 ( 1997-02-01), p. 891-903
    Abstract: TrkA high-affinity receptors are essential for the normal development of sympathetic paravertebral neurons and subpopulations of sensory neurons. Paravertebral sympathetic neurons and chromaffin cells of the adrenal medulla share an ontogenetic origin, responsiveness to NGF, and expression of TrkA. Which aspects of development of the adrenal medulla might be regulated via TrkA are unknown. In the present study we demonstrate that mice deficient for TrkA, but not the neurotrophin receptor TrkB, show an early postnatal progressive reduction of acetylcholinesterase (AChE) enzymatic activity in the adrenal medulla and in preganglionic sympathetic neurons within the thoracic spinal cord, which are also significantly reduced in number. Quantitative determinations of specific AChE activity revealed a massive decrease (−62%) in the adrenal gland and a lesser, but still pronounced, reduction in the thoracic spinal cord (−40%). Other markers of the adrenal medulla and its innervation, including various neuropeptides, chromogranin B, secretogranin II, amine transporters, the catecholamine-synthesizing enzymes tyrosine hydroxylase and PNMT, synaptophysin, and L1, essentially were unchanged. Interestingly, AChE immunoreactivity appeared unaltered, too. Preganglionic sympathetic neurons, in contrast to adrenal medullary cells, do not express TrkA. They must, therefore, be affected indirectly by the TrkA knock-out, possibly via a retrograde signal from chromaffin cells. Our results suggest that signaling via TrkA, but not TrkB, may be involved in the postnatal regulation of AChE activity in the adrenal medulla and its preganglionic nerves.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 1997
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 1998
    In:  Proceedings of the National Academy of Sciences Vol. 95, No. 1 ( 1998-01-06), p. 370-375
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 95, No. 1 ( 1998-01-06), p. 370-375
    Abstract: We used conserved domains in the major class (nucleotide binding site plus leucine-rich repeat) of dicot resistance ( R ) genes to isolate related gene fragments via PCR from the monocot species rice and barley. Peptide sequence comparison of dicot R genes and monocot R -like genes revealed shared motifs but provided no evidence for a monocot-specific signature. Mapping of these genes in rice and barley showed linkage to genetically characterized R genes and revealed the existence of mixed clusters, each harboring at least two highly dissimilar R -like genes. Diversity was detected intraspecifically with wide variation in copy number between varieties of a particular species. Interspecific analyses of R -like genes frequently revealed nonsyntenic map locations between the cereal species rice, barley, and foxtail millet although tight collinear gene order is a hallmark of monocot genomes. Our data suggest a dramatic rearrangement of R gene loci between related species and implies a different mechanism for nucleotide binding site plus leucine-rich repeat gene evolution compared with the rest of the monocot genome.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 3
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 17, No. 12 ( 1997-06-15), p. 4688-4699
    Abstract: Protease nexin-1 (PN-1), a member of the serpin superfamily, controls the activity of extracellular serine proteases and is expressed in the brain. Mutant mice overexpressing PN-1 in brain under the control of the Thy-1 promoter (Thy 1/PN-1) or lacking PN-1 (PN-1−/−) were found to develop epileptic activity in vivo and in vitro . Theta burst-induced long-term potentiation (LTP) and NMDA receptor-mediated synaptic transmission in the CA1 field of hippocampal slices were augmented in Thy 1/PN-1 mice and reduced in PN-1−/− mice. Compensatory changes in GABA-mediated inhibition in Thy 1/PN-1 mice suggest that altered brain PN-1 levels lead to an imbalance between excitatory and inhibitory synaptic transmission.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 1997
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 4
    In: Language and Speech, SAGE Publications, Vol. 41, No. 3-4 ( 1998-07), p. 443-492
    Abstract: Identifying whether an utterance is a statement, question, greeting, and so forth is integral to effective automatic understanding of natural dialog. Little is known, however, about how such dialog acts (DAs) can be automatically classified in truly natural conversation. This study asks whether current approaches, which use mainly word information, could be improved by adding prosodic information. The study is based on more than 1000 conversations from the Switchboard corpus. DAs were hand-annotated, and prosodic features (duration, pause, F0, energy, and speaking rate) were automatically extracted for each DA. In training, decision trees based on these features were inferred; trees were then applied to unseen test data to evaluate performance. Performance was evaluated for prosody models alone, and after combining the prosody models with word information—either from true words or from the output of an automatic speech recognizer. For an overall classification task, as well as three subtasks, prosody made significant contributions to classification. Feature-specific analyses further revealed that although canonical features (such as F0 for questions) were important, less obvious features could compensate if canonical features were removed. Finally, in each task, integrating the prosodic model with a DA-specific statistical language model improved performance over that of the language model alone, especially for the case of recognized words. Results suggest that DAs are redundantly marked in natural conversation, and that a variety of automatically extractable prosodic features could aid dialog processing in speech applications.
    Type of Medium: Online Resource
    ISSN: 0023-8309 , 1756-6053
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    Language: English
    Publisher: SAGE Publications
    Publication Date: 1998
    detail.hit.zdb_id: 2001596-3
    SSG: 5,2
    SSG: 7,11
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  • 5
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 1998
    In:  Proceedings of the National Academy of Sciences Vol. 95, No. 5 ( 1998-03-03), p. 2331-2336
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 95, No. 5 ( 1998-03-03), p. 2331-2336
    Abstract: Primordial germ cells (PGCs) give rise to both eggs and sperm via complex maturational processes that require both cell migration and proliferation. However, little is known about the genes controlling gamete formation during the early stages of PGC development. Although several mutations are known to severely reduce the number of PGCs reaching and populating the genital ridges, the molecular identity of only two of these genes is known: the c- kit receptor protein tyrosine kinase and the c- kit ligand (the steel factor). Herein, we report that mutant mice lacking TIAR, an RNA recognition motif/ribonucleoprotein-type RNA-binding protein highly expressed in PGCs, fail to develop spermatogonia or oogonia. This developmental defect is a consequence of reduced survival of PGCs that migrate to the genital ridge around embryonic day 11.5 (E11.5). The numbers of PGCs populating the genital ridge in TIAR-deficient embryos are severely reduced compared to wild-type embryos by E11.5 and in the mutants PGCs are completely absent at E13.5. Furthermore, TIAR-deficient embryonic stem cells do not proliferate in the absence of exogenous leukemia inhibitory factor in an in vitro methylcellulose culture assay, supporting a role for TIAR in regulating cell proliferation. Because the development of PGCs relies on the action of several growth factors, these results are consistent with a role for TIAR in the expression of a survival factor or survival factor receptor that is essential for PGC development. TIAR-deficient mice thus provide a model system to study molecular mechanisms of PGC development and possibly the basis for some forms of idiopathic infertility.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    American Association for the Advancement of Science (AAAS) ; 1997
    In:  Science Vol. 275, No. 5308 ( 1997-03-28), p. 1922-1925
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 275, No. 5308 ( 1997-03-28), p. 1922-1925
    Abstract: The electrical properties of individual bundles, or “ropes,” of single-walled carbon nanotubes have been measured. Below about 10 kelvin, the low-bias conductance was suppressed for voltages less than a few millivolts. In addition, dramatic peaks were observed in the conductance as a function of a gate voltage that modulated the number of electrons in the rope. These results are interpreted in terms of single-electron charging and resonant tunneling through the quantized energy levels of the nanotubes composing the rope.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
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    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 1997
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
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  • 7
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 1999
    In:  Psychological Research Vol. 62, No. 1 ( 1999-4-29), p. 1-19
    In: Psychological Research, Springer Science and Business Media LLC, Vol. 62, No. 1 ( 1999-4-29), p. 1-19
    Type of Medium: Online Resource
    ISSN: 0340-0727 , 1430-2772
    RVK:
    Language: Unknown
    Publisher: Springer Science and Business Media LLC
    Publication Date: 1999
    detail.hit.zdb_id: 1463034-5
    detail.hit.zdb_id: 2426389-8
    SSG: 5,2
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