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  • 1
    ISSN: 1432-1106
    Keywords: Substantia nigra ; Serotonin ; Autoreceptor ; Dopamine release ; Nigrostriatal ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Extracellular single unit recordings were obtained from antidromically identified nigrostriatal dopaminergic neurons in anesthetized rats to determine the effects of dorsal raphé stimulation on the somatodendritic excitability of substantia nigra dopaminergic neurons. Stimulation of the dorsal raphé with a brief train of pulses delivered 7–2 ms prior to the neostriatal-evoked antidromic response significantly reduced the proportion of neostriatal-evoked antidromic responses that consisted of both initial segment and somatodendritic components without significantly altering the neostriatal-evoked post-stimulus inhibitory period. Raphé stimulation alone facilitated post-stimulus neuronal firing in almost half of the cells examined. The raphé-induced decrease in somatodendritic excitability was blocked by the serotonin antagonist, metergoline (0.5–2.0 mg/kg, i.v.), without significantly affecting the rate or pattern of spontaneous activity. The tryptophan hydroxylase inhibitor, parachlorophenylalanine (400 mg/kg, i.p. for three consecutive days), abolished the decrease in somatodendritic excitability following raphé stimulation which could be re-instated by intravenous administration of 5-HTP. The dopamine antagonists haloperidol (25–100 μg/kg, i.v.) and sulpiride (10–30 mg/kg, i.v.) also blocked the effects of dorsal raphé stimulation on somatodendritic invasion. These data suggest that in vivo, serotonin liberated from raphé-nigral terminals facilitates the release of dopamine from nigrostriatal dendrites resulting in a local, autoreceptor-mediated reduction in somatodendritic excitability without affecting the spontaneous firing rate and excitability of the neuron as a whole.
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  • 2
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Interstitial cytogenetic deletions involving the paternally derived chromosome 15q11–13 have been described in patients with the Prader-Willi syndrome (PWS). We report a child with PWS and a de novo unbalanced karyotype −45,XY,−9,−15,+der(9)t(9;15)(q34;q13). Molecular studies with the DNA probe pML34 confirmed that only a single Prader Willi critical region (PWCR: 15q11.2-q12) copy was present. Hybridisation of patient and parental DNA with the multi-allelic probe CMW1, which maps to pter-15q13, showed that the chromosome involved in the translocation was paternal in origin. This is the first example of a paternally-derived PWCR allele loss caused by an unbalanced translocation that has arisen de novo.
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  • 3
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two highly conserved forms of cellular retinoic acid binding protein (CRABP-I and CRABP-II) have been described, and one, CRABP-II, is highly expressed in human skin. We have utilized a 10-kb fragment containing the human CRABP-II (hCRABP-II) gene (isolated from a human genomic library) to localize hCRABP-II to human chromosome 1 band q21 by fluorescence in situ hybridization. Localization to 1q was confirmed by hybridization of a hCRABP-II cDNA clone against a human-mouse hybrid cell line containing a t(1;6)(q21;q13) translocation chromosome. The hCRABP-II gene is therefore localized to a band known to contain several other genes that are expressed in the context of epidermal differentiation, including profilaggrin, loricrin, involucrin, and calcyclin.
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  • 4
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A 29-year-old male with Angelman syndrome and an unbalanced reciprocal translocation, 45,XY,-8,-15,+der(8),t(8;15)(p23.3;q11)pat, was evaluated with DNA studies. These showed the underlying mechanism to be paternal uniparental disomy. This is the second case reported of Angelman syndrome that has resulted from a familial unbalanced reciprocal translocation.
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  • 5
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following oral inoculation, the excretion of a virulent or an attenuated strain of bovine coronavirus in calf feces and their persistence in spiral colon, ileum, and jejunum were studied using hemagglutination and direct fluorescent antibody tests, respectively. The virus was excreted in feces for only 3 days at high titers and then intermittently at low titers. However, viral antigen was detected in crypt or Peyer's patches for at least 3 weeks after infection in 1 of 3 calves given virulent virus and 1 of 2 calves given attenuated virus.
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  • 6
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Restriction fragment heterogeneity of Hae III digestion products of cDNA to virion RNA was used to map the distribution of dengue virus topotypes found in the American region. By comparing the electrophoretic patterns of fragments produced, dengue virus isolates were placed in groups that agreed with those previously determined by oligonucleotide fingerprinting. Dengue-1 and dengue-4 viruses occur throughout the western hemisphere as single genetic types, with most of the isolates sharing at least 70% of their Hae III restriction enzyme fragments. Dengue-2 virus exists as two topotypes in the region with apparently non-overlapping distributions. The Puerto Rico topotype, which has been in the Caribbean for at least 40 years, is genetically diverse, while the Jamaica topotype, first isolated in 1981, is more homogeneous and has expanded its range from the original Caribbean focus to South America.
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  • 7
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Direct association between wheat roots and an ammonia-excreting mutant of the cyanobacterium Anabaena variabilis, strain SA-1, was required for maximal enhancement of growth of wheat plants in nitrogen (N)-free, hydroponic medium. Over 85% of the cyanobacterial mutant SA-1 inoculated to the roots were adsorbed under non-saturating conditions. The adsorption process of SA-1 to wheat roots was biphasic: an initial rapid adsorption was followed by a slow phase with about 10% of the initial adsorption rate. The maximal adsorption rate of filaments observed was 1.6 mg dry wt. SA-1 adsorbed·plant−1·h−1. Bypassing CO2 fixation and sugar formation, the 14C label from [14C]sucrose was directly applied to leaf blades to study sugar translocation. The 14C label from this treatment appeared in the wheat culture medium within an hour. Nitrate-grown plants excreted about 30% of the 14C label into the medium, compared to only 10% excreted by wheat/Anabaena co-cultures. SA-1 assimilated 27% of all 14C translocated from [U-14C]sucrose applied to wheat leaves, and 14C label from this treatment was recovered from strain SA-1 after 30 min. Roots and cyanobacteria accounted for 51% of all radioactive label recovered in the plants co-cultured with SA-1 vs 20% for nitrate-grown plants. We studied the activity of β-fructosidase (invertase) in wheat of variety Yecora rojo. Roots from nitrate-grown wheat plants produced high levels of invertase activity, which converted over 85% of 3 mm sucrose into glucose and fructose in 24 h. The rate of sucrose disappearance in the medium of co-cultures using A. variabilis SA-1, was 70% of that of nitrate-grown plants, but the levels of glucose and fructose in these cultures were always very low during sucrose conversion, suggesting hexose assimilation. To study the role of diffusible metabolites, a dialysis membrane was employed to separate the ammonia-excreting SA-1 from the wheat roots. Containing SA-1 in a dialysis bag away from direct root contact, severely limited leaf growth to less than one-third of the growth rate of nitrate control cultures. Ammonia produced by mutant SA-1 in dialysis bag cultures was excreted into the medium at 0.4 mm vs 1.2 mm in free-living cultures, but ammonia was not detectable in co-cultures with or without the dialysis bag containing the mutant. The nitrogenase activity derepressed in the mutant and responsible for ammonia excretion was always higher in the association co-cultures than in either free cells or in dialysis-bag cultures. The nitrogenase activity of strain SA-1 was highest (200 μmol ethylene formed·mg−1 Chl·h−1) when the cyanobacterium was associated with the root tips. Dialysis membrane separation of plant and cyanobacterium severely inhibited growth of wheat during a complete growth cycle of 2 months. Total biomass and grain yield were very similar for control cultures without inorganic N or SA-1, and for diffusion cultures containing SA-1, kept in a dialysis bag around the roots. Total biomass of the association co-culture attained 75% of the biomass of the nitrate-grown control. It is proposed that wheat roots supplied fructose derived from sucrose for growth and nitrogen fixation of SA-1 in the light, and that ammonia excreted by SA-1 was utilized by the wheat plant for its own growth.
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  • 8
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    Integral equations and operator theory 13 (1990), S. 593-606 
    ISSN: 1420-8989
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A geometric condition for the existence of bounded evaluations is given. Using this criterion for sets of finite perimeter, it is shown that P2(wdm2) has analytic bounded point evaluations, when w is of bounded variation with compact support. This theorem is then related to previous work on bounded point evaluations.
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  • 9
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The release of glutamate from neuron-free cultures of neo-cortical astrocytes was monitored using high-performance liquid chromatography (HPLC). The neuroligand bradykinin (lOOnM) increased glutamate in the superfusate ("=16; /)〈0.02, paired /-test; Fig. \a). To investigate whether internal ...
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  • 10
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] TF55 was purified from the soluble portion of Triton X-100 cell extracts by anion exchange chromatography and glycerol gradient sedimentation. Most of the TF55 sedimented in the gradient at 20S (Fig. la). No nucleic acid was found by spectro-photometry in the 20S fraction, suggesting that ...
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