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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 49 (1980), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Photosynthetic and anatomical parameters of leaves from the juvenile and adult part of an ivy plant (Hedera helix L.) have been determined and compared with each other. Light-saturated net photosynthesis (per unit leaf area) was about 1.5 times higher in adult leaves than in juvenile ones. The lower photosynthetic capacity of juvenile leaves was caused by a lower stomatal and especially a lower residual conductance to the CO2-transfer. This corresponds with anatomical features of the leaves, i.e. lower stomatal frequency, fewer chloroplasts per cell, and – most important – thinner leaves, as well as with a less efficient photosynthetic apparatus measured as Hill reaction of isolated broken chloroplasts and activity of ribulose bisphosphate carboxylase. No differences in the respiration in light (relative to net photosynthesis) and in the CO2-compensation concentration could be detected between the two leaf types. These observed anatomical and photosynthetic parameters of the juvenile and adult ivy leaves resemble those reported for shade and sun leaves, respectively, although the leaves investigated originated from the same light environment.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 16S rRNA gene libraries were prepared by polymerase chain reaction amplification and cloning from soil samples taken periodically from a field with genetically modified plants. Sequence analyses of the cloned rDNAs indicated that 140 of them clustered apart from known bacterial phyla. Based on 31 full sequences a new phylum could be defined. It includes Holophaga foetida, ‘Geothrix fermentans’ and Acidobacterium capsulatum as the only cultured species so far. Therefore, this line of descent was named the Holophaga/Acidobacterium phylum. About 50 published partial sequences of cloned rDNAs retrieved from soil, freshwater sediments or activated sludge from different continents indicate the occurrence of further representatives of this phylum. Two specific hybridization probes were constructed for members of one of four subclusters. A careful data analysis revealed the importance and problems of identifying and dealing with artefacts such as chimeric structure when defining new phylogenetic groups based mainly upon cloned amplified rDNAs. For the first time, the presence of bacterial cells representing this group could be shown in soil, sediment, activated sludge and lake snow by in situ hybridization.
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Heparin, a highly sulfated glycosaminoglycan, is known to be obligatory for long-term endothelial cell cultures; it potentiates the mitogenic activities of endothelial cell growth factors and prolongs the replicative life span of the cells. Here we have shown that besides its growth factor-supportive role, heparin exerts a specific action on cerebral capillary endothelial cells (cECs), unrelated to serum or growth factors, by increasing activity of ornithine decarboxylase (ODC; EC 4.1.1.17) in these cells. For our experiments we have used two different types of cloned cECs: type I cECs, grown in the presence of endothelial cell growth factor and heparin, and type II cECs, usually cultivated without growth factors. Heparin action on ODC activity was shown to be dose dependent within the range of 1–100 μg/ml. Increasing concentrations of or depletion of endothelial cell growth factor from type I cultures had no effect on ODC activity. The increase in enzyme activity was highest after 30 min to 1 h of heparin treatment. As evidenced by northern analysis, the heparin-mediated enhancement of ODC activity was not accompanied by changes of ODC mRNA levels. Studies of DNA replication revealed that in the absence of heparin-binding growth factors, heparin did not affect the proliferative activity of cloned cECs.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Birth 10 (1983), S. 0 
    ISSN: 1523-536X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The variable designs and results of controlled trials of maternal position in labor are summarized. Following Mendez-Bauer 's design, the effects of sitting alternated with side-lying and supine alternated with side-lying were compared in terms of contraction intensity and frequency, uterine activity and efficiency, and maternal comfort. The effects of each position were influenced by the position it was alternated with and the phase of labor during which it was used. While contractions were more frequent when sitting, uterine activity and efficiency were greater while side-lying, both in early and late labor. There was no statistically significant difference in uterine activity or efficiency in the side lying position when compared to the supine (propped) position although contractions were more intense and less frequent while sidelying. These results suggest that position change is important in achieving efficient uterine contractions. (BIRTH 10:4, Winter 1983)
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Ascorbate is present in millimolar concentrations in mammalian brain and can be released from cellular stores by membrane depolarization. We report here that physiologically relevant concentrations of ascorbate modulate 5-[3H]hydroxytryptamine ([3H]5-HT) binding to bovine frontal cortex membranes. Under conditions where [3H]5-HT binding is reversible and saturable, ascorbate causes a concentration-dependent increase in the affinity of [3H]5-HT for central 5-HT3 binding sites. At pH 7.4, increasing ascorbate from 0 to 5.7 mM changes the equilibrium affinity constant (KD) of binding to 5-HT3 sites from 125 nM to 30 nM, without affecting binding site number. These ascorbate-induced effects are pH dependent. At pH 7.1 binding to central 5-HT3 sites is essentially eliminated in the presence of ascorbate. These studies suggest that ascorbate and hydrogen ion concentration interactions may modulate serotonergic function.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 49 (1987), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Uptake of carnosine has been investigated in as-troglia-rich primary cultures derived from brains of newborn mice. It could be demonstrated that carnosine is not degraded by these cells but rapidly taken up in an energy and sodium-dependent process. Uptake and release of carnosine by these cells were found to be mediated by a saturable, high-affinity transport system with apparent kinetic constants of Km=50 μMand Vmax= 22.7 nmol h1 mg protein1. Uptake of carnosine is strongly inhibited by other dipeptides as well as by various oligopeptides, e.g., Leu-en-kephalin. However, uptake of the radiolabeled tripeptide D Ala-L-Ala-L-Ala was not observed. Radiolabeled Leu-en-kephalin also did not accumulate intracellularly, even if degradation of the peptide was prevented by use of peptidase inhibitors. These results suggest that uptake of carnosine is catalyzed by a dipeptide-specific transport system with broad substrate specificity. With neuronal cells in primary culture, uptake of carnosine or other peptides was not observed.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 39 (1982), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Synaptosomes were isolated from rat cerebral cortex and incubated with [U-14C]-, [1-14C]- or [6-14C]glucose. Glucose utilization and the metabolic partitioning of glucose carbon in products were determined by isotopic methods. From the data obtained a carbon balance was constructed, showing lactate to be the main product of glucose metabolism, followed by CO2, amino acids and pyruvate. Measuring the release of 14CO2 from glucose labelled in three different positions allowed the construction of a flow diagram of glucose carbon atoms in synaptosomes, which provides information about the contribution of the various pathways of glucose metabolism. Some 2% of glucose utilized was calculated to be degraded via the pentose phosphate pathway. Addition of chlorpromazine, imipramine or haloperidol at concentrations of 10−5M reduced glucose utilisation by 30% without changing the distribution pattern of radioactivity in the various products.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 14 (1967), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
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  • 9
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The haematopoietic growth factor erythropoietin is the primary regulator of mammalian erythropoiesis and is produced by the kidney and the liver in an oxygen-dependent manner. We and others have recently demonstrated erythropoietin gene expression in the rodent brain. In this work, we show that cerebral erythropoietin gene expression is not restricted to rodents but occurs also in the primate brain. Erythropoietin mRNA was detected in biopsies from the human hippocampus, amygdala and temporal cortex and in various brain areas of the monkey Macaca mulatta. Exposure to a low level of oxygen led to elevated erythropoietin mRNA levels in the monkey brain, as did anaemia in the mouse brain. In addition, erythropoietin receptor mRNA was detected in all brain biopsies tested from man, monkey and mouse. Analysis of primary cerebral cells isolated from newborn mice revealed that astrocytes, but not microglia cells, expressed erythropoietin. When incubated at 1% oxygen, astrocytes showed 〉l OO-fold time-dependent erythropoietin mRNA accumulation, as measured with the quantitative reverse transcription-polymerase chain reaction. The specificity of hypoxic gene induction in these cells was confirmed by quantitative Northern blot analysis showing hypoxic up-regulation of mRNA encoding the vascular endothelial growth factor, but not of other genes. These findings demonstrate that erythropoietin and its receptor are expressed in the brain of primates as they are in rodents, and that, at least in mice, primary astrocytes are a source of cerebral erythropoietin expression which can be up-regulated by reduced oxygenation.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The present study extends knowledge of the basic properties of correlated oscillatory activity patterns in the visual cortex of anaesthetized cats. Recordings with multiple electrodes were performed in area 18 and the correlations of multi-unit activity in the frequency range 35-80 Hz were determined using the coherence function. Statistical analysis revealed that the multi-unit correlations depended on the cortical distance between the recording sites, the orientation selectivity of the neurons and their cortical layer. On average, correlations dropped to chance level within several millimetres and were higher in lower than in upper cortical layers. Similar results were found by analysing the correlations of oscillatory patterns in local field potentials recorded from the same electrodes. Correlations of neurons with similar orientation preferences were higher than those of neurons with different orientation preferences. Comparison to a matched sample from area 17 showed that the correlations in areas 18 and 17 depended on similar properties of the neurons. The dependences of correlated oscillations resembled the known pattern and specificity of intra-areal fibre connections, suggesting that the correlations were intracortically established. Since correlations were specifically and not randomly related to the response properties of cortical neurons and were prominent in a visual area other than area 17, the findings suggest that correlated oscillatory activity provides a potential neural code supporting sensory information processing.
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