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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Biological and immunological properties of recombinant human, rat, and chicken nerve growth factors (NGFs) were studied and compared. Recombinant NGF proteins were produced in a transient expression system using COS cells and levels of secreted NGF protein were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of conditioned media from in vivo [35S]cysteine-labeled cell cultures. Antigenic differences among the three NGFs were studied by immunoblotting and immunoprecipitation of secreted cell products using a rabbit polyclonal antiserum against purified mouse NGF, and by a two-site enzyme im-munoassay (EIA) with a monoclonal antibody against mouse NGF. Although all three NGFs were recognized equally well in the immunoblotting, only one-third of the chicken NGF protein could be detected by immunoprecipitation or by the EIA as compared to the rat and human NGFs. Thus, changes in the three-dimensional structure of the NGF molecule are most likely responsible for the antigenic differences between avian and mammalian NGFs. The three NGF proteins were also compared in their ability to displace 125I-mouse NGF from low-affinity NGF receptors on rat pheochromocytoma PC12 cells. Similar displacement curves and values were obtained for each NGF protein, indicating that structural differences among these molecules do not affect low-affinity binding to NGF receptors. Biological activities were studied by the ability of the conditioned media to promote neurite outgrowth from explants of 9 chick sympathetic ganglia and from PC12 ceils. Although the rat system showed a slight preference for the homologous molecule, the morphological changes, dose-response curves, and maximal stimulation values obtained with the different NGFs were practically indistinguishable in the chicken bioassay. The observed differences and similarities among the three NGF proteins are discussed in the context of their evolutionary relationship and their potential therapeutic applications.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 5 (1993), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Degenerate primers from conserved regions in nerve growth factor, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) were used in the polymerase chain reaction to isolate DNA fragments from the chicken BDNF and NT-3 genes. A genomic clone coding for chicken NT-3 was isolated and the structure of the chicken NT-3 mature protein was subsequently deduced from nucleotide sequence analysis of the isolated chicken NT-3 gene. Comparison of the chicken BDNF and NT-3 with the corresponding rat molecules showed that the avian molecules are very similar to their mammalian homologues. Northern blot analyses of messenger RNA (mRNA) from chicken embryos from embryonic day 3.5 (E3.5), E4.5, E8, E12 and E18 showed that expression of both BDNF and NT-3 mRNA peaked at E4.5 and decreased at later stages of development. Both probes revealed two transcripts; larger mRNAs of 4.5 kilobases (kb) for BDNF and 4.0 kb for NT-3 predominated over the smaller transcripts of 1.4 and 1.3 kb, respectively. The cellular localization of BDNF and NT-3 mRNA in the E4 and E6 embryos was studied by in situ hybridization. In the E4 embryo, labelling for BDNF was seen over cells in restricted parts of the epithelium of the otic vesicle. Analysis of adjacent sections for the low-affinity nerve growth factor receptor mRNA showed that regions in the otic vesicle epithelium which labelled for BDNF mRNA also labelled for low-affinity nerve growth factor receptor mRNA. No labelling for NT-3 was detected in the otic vesicle. Labelling for BDNF mRNA was also found over mesenchyme dorsal to the wing bud, in the wing bud and in the splanchnopleural lining of the stomach. Labelling for NT-3 mRNA was found at E4 over the epidermis on the ventral side in the region of the branchial arches. The labelling extended up the maxillary processes to Rathke's pouch. The closely located infundibulum was weakly labelled for NT-3 mRNA. NT-3 mRNA was also detected in the mesenchyme surrounding the oesophagus and lung buds. The regional expression pattern is in agreement with the established role for BDNF and NT-3 as target-derived neurotrophic factors, but the results also suggest that BDNF may be an intrinsic factor important for the development of the inner ear. The results support the emerging view that neurotrophic factors can play a role in early differentiation of both neuronal and non-neuronal tissues.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 286 (1980), S. 25-28 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Nerve growth factor (NGF) activity was not detected by bioassay in irides killed immediately after excision but NGF appeared within 24 h in living irides placed in culture or grafted to a host eye. Furthermore, sensory and, although less effective, sympathetic denervation of irides in situ led ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 36 (1980), S. 508-510 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0738
    Keywords: Testicular atrophy ; NGF ; Male germ cells ; spermatozoa ; Toluene ; Xylene ; n-Hexane ; Combined exposure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Testicular and germ cell line morphology in rats were studied 2 weeks, 10 months and 14 months after cessation of a 61-day inhalation exposure to 1000 ppm n-hexane. Androgen biosynthetic capacity of testis, testosterone blood concentration, vas deferens morphology and noradrenaline (NA) concentration, epididymal sperm morphology, and fertility were also studied. Severe testicular atrophy involving the seminiferous tubules with loss of the nerve growth factor (NGF) immunoreactive germ cell line was found. Total loss of the germ cell line was found in a fraction of animals up to 14 months post-exposure, indicating permanent testicular damage. No impairment of androgen synthesis or androgen dependent accessory organs was observed. Simultaneous administration of 1000 ppm n-hexane and 1000 ppm toluene, or 1000 ppm n-hexane and 1000 ppm xylene, did not cause germ cell line alterations or testicular atrophy. Toluene and xylene were thus found to protect from n-hexane induced testicular atrophy.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1106
    Keywords: Nerve growth factor ; Electrophysiology ; Transplant ; Brain ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have investigated the electrophysiological effects of nerve growth factor (NGF) on single-neuron activity in central nervous system (CNS) grafts of septum, spinal cord, and hippocampus in oculo. NGF was found to have slow-onset, long-lasting excitatory effects on the spontaneous firing of neurons in septal grafts, while no such effects were found in neurons of either hippocampal or spinal cord grafts. Pretreatment with an antibody against the p75 low-affinity NGF receptor blocked the NGF-induced excitations. A second NGF application caused much stronger excitatory responses in sensitive neurons. Our data suggest that forebrain cholinergic neurons may be selectively sensitive to NGF also at the neurophysiological level, responding by excitations, and that NGF upregulates these responses within less than an hour.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1459
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neurotrophin-mediated mechanisms are integral to development and maintenance of the adult central nervous system. Neurotrophin expression has been shown to change rapidly in response to many different types of neuronal stress such as excitotoxic injury, mechanical lesions, epileptogenesis and ischemia. It therefore appears as if they are not only to be regarded as target-derived trophic factors in the classical sense, but also as providers of local trophic support and neuronal protection. These discoveries suggest that neurotrophins or compounds with neurotrophin-like actions might become useful in developing new treatment strategies, not only for neurodegenerative diseases, but also for other diseases and injuries to the nervous system including stroke.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1459
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The neutrotrophins stimulate survival and differentiation of a range of target neurons. A wealth of evidence suggests that central cholinergic neurons depend on nerve growth factor (NGF) for trophic support. Grafts of NGF-producing cells rescue axotomized basal forebrain cholinergic neurons and reduce cholinergic cell death in the medial septum. Skeletal muscle cells, immortalized from embryonic day 15 (E15) rat embryos for transplantation purposes, were transfected with a human NGF construct and individual clones tested for NGF production by a biological assay using embryonic sympathetic ganglia. Clone RM22 showed a consistent ability to produce human recombinant NGF in high concentration; RM22 cells were grafted to the rat brain, following fimbria-fornix lesions, in order to examine the influence of these cells on basal forebrain cholinergic neurons. The results suggest that implantation of genetically modified cells, engineered by the introduction of expression plasmids or viral constructs to produce NGF or other neurotrophins may have therapeutic applications in rescuing damaged central cholinergic neurons in senile dementia of the Alzheimer type as well as in providing trophic support for chromaffin tissue grafts in Parkinson's disease. Moreover, the use of genetically engineered cells may be used to study the effects of administering tailor-made neurotrophins with novel activity profiles.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The localization of substance P (SP) or a SP-like peptide in cultured spinal ganglia from chick embryos was studied by the indirect immunofluorescence technique. Ganglia from 8–16 days old chick embryos and from newly hatched chickens were cultured in a control medium or in the presence of nerve growth factor (NGF). Addition of colchicine and exposure to different explanted peripheral tissues were also tried. Ganglia from the younger embryos (8–12 days) cultured for 24 h with added NGF showed a weak SP-like immunoreactivity (SPLI) in some cell bodies and strong specific immunofluorescence in nerve fibres growing out from the ganglia. In spinal ganglia of the older embryos (14 and 16 days) and newly hatched chickens cultured with and without NGF the concentration of SPLI in the cell bodies was considerably higher. Addition of colchicine to spinal ganglia cultured 12 h in NGF-medium, resulted in retraction of nerve fibres and strongly fluorescent, expanded nerve fibres were observed in peripheral parts of the ganglia. Explants of skin placed near the spinal ganglia stimulated the outgrowth of fibres, some of them containing SPLI. A few fluorescent fibres were also seen within the skin explants. Also heart tissue explants stimulated outgrowth of nerve fibres, but innervation of these explants with SPLI-containing nerves could not be observed. Nerve fibre-extension from the spinal ganglia was not stimulated by spinal cord explants. The present results support the existence of SP-containing primary sensory neurons in chickens.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 9 (1980), S. 665-682 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nodose ganglia from 8-day-old chick embryos were cultured in collagen gels for 2 days, with or without added nerve growth factor (NGF), in order to discover whether the nodose neurons, derived from an epidermal placode, are susceptible to this trophic factor. Neuronal survival and neurite outgrowth were stimulated only after addition of NGF, and the enhancing effects could be blocked by introducing antibodies to NGF. Stereological analysis of ganglia sectioned for light microscopy showed that the NGF-treated neurons increased their volume by about 50%, as did the nodose neurons in ovo from the eighth to the tenth day of incubation. The volume density, however, was significantly lowerin vitro indicating a limited cell death during culture despite the presence of exogenously supplied NGF. The number of neurofilaments and microtubules increased in the cell centre of neurons treated with NGF; this region also showed numerous dense bodies and an extensive Golgi complex by electron microscopy. Ultrastructural similarities between neurons responding to NGF and neurons undergoing the axon reaction which follows axotomy are indicated. A role for a trophic factor resembling NGF in the normal development of placode-derived neurons of the sensory cranial ganglia is suggested.
    Type of Medium: Electronic Resource
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