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  • 1
    ISSN: 0300-9629
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0920-9964
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0920-9964
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0983
    Keywords: Mitochondria ; DNA ; Fungus ; Allomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have demonstrated by gel analysis of restricted DNA paternal inheritance of mitochondrial DNA in interspecific crosses between A. macrogynus and A. arbuscula.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 78 (1971), S. 76-91 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The leucine-lysine synchronization technique of Dill and Fuller (1970) has been further refined and used to study various biosynthetic events of pre-mitotic germlings of Allomyces neo-moniliformis (the time of DNA replication, RNA synthesis, and protein synthesis), and various morphogenetic changes (germling development, nuclear cap breakdown, and the first mitotic nuclear division). The degree of synchrony induced in a population of germlings appears to be determined by the time when the zoospores are induced to encyst and germinate rather than by the duration of the swimming period of the zoospore. DNA replication, nuclear cap breakdown, early protein synthesis, and morphogenetic development appear to occur prior to messenger RNA synthesis in developing thalli and thus would be under the control of pre-existing messenger RNA. The degree of synchrony of particular morphogenetic or biosynthetic developmental changes induced in a population of A. neo-moniliformis germlings must be determined for each aspect of development which is to be studied.
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  • 6
    ISSN: 1432-1106
    Keywords: Key words Nerve growth factor ; Brain-derived neurotrophic factor ; Locomotion ; Nicotinic receptor ; Intracerebroventricular administration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The acute and subacute effects of intracerebroventricularly (ICV) administered nerve growth factor (NGF) or brain-derived neurotrophic factor (BDNF) on locomotor activity were evaluated in awake adult rats. Immediately after ICV injection through an implanted cannula, locomotor activity was measured by a computerized system using infrared photocells, which allowed us to record locomotion, motility, and rearing simultaneously. A single dose of 5 μg mouse β-NGF produced significant increases in horizontal ambulatory components of locomotor activity (locomotion and motility), but not vertical movement (rearing) 30–45 min after ICV administration. These increases lasted for at least 3–4 h. Systemic injection of 2.0 mg/kg mecamylamine, a central nicotinic receptor antagonist, inhibited the hyperactivity induced by NGF. Systemic injection of 0.5 mg/kg scopolamine, a muscarinic receptor antagonist, did not interfere with the NGF effects. Thus, while scopolamine induced marked increases in all three measures of behavior in both NGF and cytochrome-c-treated animals, locomotion and motility remained significantly higher in the NGF group. Immunohistochemistry demonstrated that NGF diffused readily from the ventricular space into brain parenchyma on the injected side and could be visualized 1 h after ICV injection. These results suggest that ICV administration of NGF increases locomotor activity by inducing acetylcholine release, and that nicotinic receptors are involved in the hyperactivity induced by NGF. ICV administration of 5 μg recombinant human BDNF had no significant effect on locomotor activity during the 0- to 4-h period after ICV injection. However, it produced significant decreases in locomotion, motility, and rearing 24–26 h later. Hence ICV administration of BDNF has entirely different effects on animal behavior from those evoked by NGF. While NGF elicits increases in ambulatory behavior within hours, BDNF causes delayed decreases in ambulatory behavior.
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  • 7
    ISSN: 1432-1106
    Keywords: Brain grafts ; Substantia nigra ; Electrophysiology ; Dopamine agonists ; Dopamine antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pieces of fetal rat mesencephalon containing the substantia nigra were transplanted into the lateral ventricle of rats pretreated with 6-OHDA injections into the ipsilateral substantia nigra. Extracellular recordings from these grafts revealed spontaneously active neurons with action potential waveforms and firing rates similar to those found in substantia nigra zona compacta in situ. Furthermore, local application of dopamine agonists inhibited, while dopamine antagonists increased zona compacta activity, both in situ and of cells from nigral grafts. We conclude that substantia nigra grafts contain spontaneously active neurons similar to those of zona compacta in situ, and that some of the mechanisms regulating nigral neuronal activity in situ are also present in this preparation.
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  • 8
    ISSN: 1432-1106
    Keywords: Astrocytes ; Glial fibrillary acidic protein ; Image analysis ; Aging ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Smears of fresh rat brain tissue combined with immunohistochemistry using antiserum to glial fibrillary acidic protein (GFA) were used to visualize individual astrocytes in different cortical regions of rats ranging in age from 1 to 30 months. By computerized image analysis, the cell area and the cell perimeter were determined. Using 4-month-old male Sprague-Dawley rats, it was found that GFA-positive astrocytes from cerebellum and hippocampus were significantly larger, both in terms of cell area and cell perimeter, than similar cells from cortex cerebri. The temporal development was carefully followed in smears of the hippocampal formation where a continuous increase in cell size was observed from 1 to 30 months of age. During the first few postnatal months a rapid increase in both cell area and cell perimeter was observed using Sprague-Dawley rats. For studies of senescent animals, Fisher 344 rats specifically bred for aging studies were obtained. Using such animals, a second, highly significant slower growth phase which continued until the longest time points studied was observed. A separate experiment using Sprague-Dawley rats also showed large differences in both cell area and cell perimeter of GFA-positive cerebellum and cortical astrocytes taken from 6-week- and 18-month-old animals. In conclusion, the present study shows that maturation of GFA-positive astrocytes is a process which continues for several months postnatally. This relatively rapid growth phase is followed by a slower increase in cell size, probably continuing throughout life.
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  • 9
    ISSN: 1432-1106
    Keywords: Sustained seizures ; GFA ; Laminin ; Neurofilament ; Immunohistochemistry ; Epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sustained experimental seizures in rats have previously been shown to cause an extensive necrosis in pars reticulata of substantia nigra (SNPR) and globus pallidus (GP). In the present paper we have studied the effects of hexafluorodiethyl ether-induced seizures on the immunoreactivity seen with antibodies directed against glial fibrillary acidic protein, GFA, used to visualize astrocytes, antibodies to the glycoprotein laminin as a marker for blood vessel walls and neurofilament (NF) antibodies to monitor neuronal disturbances. Already 12 h after a 20-min seizure period a reduction in GFA immunofluorescence intensity was observed in SNPR. After 3 days, marked lesions were noted in SNPR and GP as seen with cresyl violet staining. The lesions contained almost no GFA-positive structures. In the proximity of the lesions, an increase in GFA-immunoreactivity was noted. Such an increase, although less pronounced, was also seen in the major projection areas of SNPR. Two months post-seizure, the gliotic reaction had disappeared, and only a thin and elongated gliotic scar was observed. In spite of the development of a profound central necrosis especially evident in SNPR, both laminin-and NF-immunoreactivity was slightly increased within the lesioned areas. NF-immunoreactivity was also increased in the superior colliculus and in the reticular formation. Two months post-experiment NF-immunofluorescence was normalized but the former lesion sites showed signs of hypervascularization. We conclude that hexafluorodiethyl ether-induced 20-min seizures lead to rapid, localized glial and neuronal changes in the rat brain as evidenced by GFA and NF immunohistochemistry, while the vascular network remains intact.
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  • 10
    ISSN: 1432-1106
    Keywords: NGF ; Basal forebrain ; Septum ; Intraocular graft ; Choline acetyltransferase ; Acetylcholinesterase histochemistry ; Acetylcholinesterase antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of nerve growth factor (NGF) on developing central cholinergic neurons were studied using intraocular grafts of rat fetal (E17) basal forebrain tissue. Prior to grafting, grafts were incubated in NGF or saline. Transplants were allowed to mature for six weeks, receiving weekly intraocular injections of NGF or saline. Measurements of NGF levels in oculo after one single injection showed that NGF slowly decreases in the anterior chamber fluid, and after one week, low but significant levels were still present in the eye. Following pretreatment with diisopropylfluorophosphate (DFP), the cholinergic neurons in the grafts were analyzed using three morphological markers: antibodies to cholineacetyltransferase (ChAT), antibodies to acetylcholinesterase (AChE Ab) and acetylcholinesterase histochemistry (AChE). The transplants grew well and became vascularized within the first week. The growth of the NGF-treated basal forebrain grafts was significantly enhanced as compared to the growth of the saline-treated grafts evaluated with repeated stereomicroscopical observations directly through the cornea of the etheranaesthetized hosts. The NGF-treated grafts contained almost twice as many cholinergic neurons seen with all the cholinergic markers used, as the salinetreated grafts. However, there was no difference in cholinergic cell density between the two groups. The morphology and size of an individual cholinergic neuron was similar in the two groups. The fiber density as evaluated with AChE-immunohistochemistry did not change after NGF-treatment. The DFP-treatment did not seem to affect the AChE-immunoreactivity since an extensive fiber network was found, whereas almost no fibers were seen using conventional AChE histochemistry. We have demonstrated that in oculo transplantation of basal forebrain is a useful model for examining in vivo effects of NGF on central cholinergic function. The marked volume increase of NGF-treated grafts and the unchanged density of cholinergic cells and terminals suggests, that NGF increases the survival of not only developing cholinergic neurons, but possibly other non-cholinergic neurons and non-neuronal cells as well. These results support the notion that NGF acts as a neurotrophic factor on cholinergic and possibly non-cholinergic cells in the central nervous system
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