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Sökning: WFRF:(Hallböök F)

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1.
  • Friedman, W J, et al. (författare)
  • Differential actions of neurotrophins in the locus coeruleus and basal forebrain.
  • 1993
  • Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886 .- 1090-2430. ; 119:1, s. 72-8
  • Tidskriftsartikel (refereegranskat)abstract
    • The neurotrophin gene family, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and NT-4/NT-5, supports the survival of distinct peripheral neurons, however, actions upon central neurons are relatively undefined. In this study we have compared different neurotrophins in the regulation of neuronal survival and function using dissociated embryonic cell cultures from two brain regions, the basal forebrain (BF) and locus coeruleus (LC). In the BF, NGF increased choline acetyl transferase (ChAT) activity, but did not influence cholinergic cell survival. In contrast to NGF, BDNF, NT-3, and the novel neurotrophin, NT-4, all increased ChAT activity and cholinergic cell survival. We also examined embryonic LC neurons in culture. LC neurons are unresponsive to NGF. In contrast, NT-3 and NT-4 elicited significant increases in survival of noradrenergic LC neurons, the first demonstration of trophic effects in this critical brain region. Identification of factors supporting coeruleal and basal forebrain neuronal survival may provide insight into mechanisms mediating degeneration of these disparate structures in clinical disorders.
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2.
  • Ibáñez, C F, et al. (författare)
  • Expression of neurotrophin-4 mRNA during oogenesis in Xenopus laevis.
  • 1992
  • Ingår i: International Journal of Developmental Biology. - 0214-6282 .- 1696-3547. ; 36:2, s. 239-45
  • Tidskriftsartikel (refereegranskat)abstract
    • Neurotrophin-4 (NT-4), a recently discovered novel member of the family of neurotrophic factors structurally related to nerve growth factor (NGF), is abundantly expressed in the Xenopus laevis ovary. In this study we have localized NT-4 mRNA expressing cells in the Xenopus ovary by in situ hybridization and have used this technique together with Northern blot analyses to quantify NT-4 mRNA expression during oogenesis in Xenopus. In situ hybridization of sections through the Xenopus ovary using an alpha-[35S]-dATP labeled Xenopus NT-4 mRNA specific probe showed an intense labeling over the cytoplasm of oocytes with a diameter of 50-200 microns corresponding to stage I according to Dumont (1972). Labeling was also seen over the cytoplasm of stages II to IV although with a lower intensity than over stage I oocytes. No labeling was seen over more mature oocytes of stages V and VI. NT-4 mRNA could not be detected in the early embryo from the onset of cleavage division to the neurula stage suggesting that the NT-4 gene is not expressed during Xenopus early embryogenesis. The confinement of NT-4 mRNA in the Xenopus ovary to immature oocytes suggests that NT-4 mRNA expression is strictly regulated during oogenesis and that the NT-4 protein could play a role as a maturation factor for immature oocytes.
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4.
  • Hallböök, F, et al. (författare)
  • Evolutionary studies of the nerve growth factor family reveal a novel member abundantly expressed in Xenopus ovary.
  • 1991
  • Ingår i: Neuron. - 0896-6273 .- 1097-4199. ; 6:5, s. 845-58
  • Tidskriftsartikel (refereegranskat)abstract
    • Evolutionary conservation of members of the NGF family in vertebrates was studied by DNA sequence analysis of PCR fragments for NGF, BDNF, and NT-3 from human, rat, chicken, viper, Xenopus, salmon, and ray. The results showed that the three factors are highly conserved from fishes to mammals. Phylogenetic trees reflecting the evolution and speciation of the members of the NGF family were constructed. In addition, the gene for a fourth member of the family, neurotrophin-4 (NT-4), was isolated from Xenopus and viper. The NT-4 gene encodes a precursor protein of 236 amino acids, which is processed into a 123 amino acid mature NT-4 protein with 50%-60% amino acid identity to NGF, BDNF, and NT-3. The NT-4 protein was shown to interact with the low affinity NGF receptor and elicited neurite outgrowth from explanted dorsal root ganglia with no and lower activity in sympathetic and nodose ganglia, respectively. Northern blot analysis of different tissues from Xenopus showed NT-4 mRNA only in ovary, where it was present at levels over 100-fold higher than those of NGF mRNA in heart.
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5.
  • Ibáñez, C F, et al. (författare)
  • Biological and immunological properties of recombinant human, rat, and chicken nerve growth factors : a comparative study.
  • 1991
  • Ingår i: Journal of Neurochemistry. - 0022-3042 .- 1471-4159. ; 57:3, s. 1033-41
  • Tidskriftsartikel (refereegranskat)abstract
    • 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 immunoassay (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 E9 chick sympathetic ganglia and from PC12 cells. 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.(ABSTRACT TRUNCATED AT 250 WORDS)
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6.
  • Ibáñez, C F, et al. (författare)
  • Structure-function studies of nerve growth factor : functional importance of highly conserved amino acid residues.
  • 1990
  • Ingår i: EMBO Journal. - 0261-4189 .- 1460-2075. ; 9:5, s. 1477-83
  • Tidskriftsartikel (refereegranskat)abstract
    • Selected amino acid residues in chicken nerve growth factor (NGF) were replaced by site-directed mutagenesis. Mutated NGF sequences were transiently expressed in COS cells and the yield of NGF protein in conditioned medium was quantified by Western blotting. Binding of each mutant to NGF receptors on PC12 cells was evaluated in a competition assay. The biological activity was determined by measuring stimulation of neurite outgrowth from chick sympathetic ganglia. The residues homologous to the proposed receptor binding site of insulin (Ser18, Met19, Val21, Asp23) were substituted by Ala. Replacement of Ser18, Met19 and Asp23 did not affect NGF activity. Modification of Val21 notably reduced both receptor binding and biological activity, suggesting that this residue is important to retain a fully active NGF. The highly conserved Tyr51 and Arg99 were converted into Phe and Lys respectively, without changing the biological properties of the molecule. However, binding and biological activity were greatly impaired after the simultaneous replacement of both Arg99 and Arg102 by Gly. The three conserved Trp residues at positions 20, 75 and 98 were substituted by Phe. The Trp mutated proteins retained 15-60% of receptor binding and 40-80% of biological activity, indicating that the Trp residues are not essential for NGF activity. However, replacement of Trp20 significantly reduced the amount of NGF in the medium, suggesting that this residue may be important for protein stability.
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8.
  • Söderström, S, et al. (författare)
  • Recombinant human beta-nerve growth factor (NGF) : biological activity and properties in an enzyme immunoassay.
  • 1990
  • Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 27:4, s. 665-77
  • Tidskriftsartikel (refereegranskat)abstract
    • Nerve growth factor (NGF) supports sympathetic and sensory neurons in the peripheral nervous system and also functions in the development and maintenance of cholinergic neurons in the basal forebrain. NGF distribution can be studied in the brain of the rat and mouse with the use of a sensitive two-site enzyme immunoassay (EIA) for mouse NGF. It would be of interest to measure the NGF protein also in the human brain, especially against the background that the cholinergic neurons are severely deteriorated in senile dementia of the Alzheimer type. The limited immunological cross-reactivity between NGFs from different species has previously hampered attempts to determine levels of the human NGF. We have now examined the biological activity and immunological properties of human recombinant NGF protein in medium conditioned by COS cells transfected with the human NGF gene. The human NGF behaved similar to mouse NGF in a sympathetic ganglion bioassay. The monoclonal antibody 27/21 to mouse NGF was shown to effectively block the activity of both the human recombinant NGF and mouse native NGF. A two-site EIA using monoclonal antibody 27/21 was optimized. Under the conditions used, the EIA detected the human recombinant NGF with the same sensitivity (1 pg/ml) as shown for the mouse NGF. It should now be possible to test this EIA also on homogenized tissue to examine human NGF in brain samples from Alzheimer patients and age-matched controls.
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9.
  • Ayer-LeLievre, C, et al. (författare)
  • Nerve growth factor mRNA and protein in the testis and epididymis of mouse and rat.
  • 1988
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 85:8, s. 2628-32
  • Tidskriftsartikel (refereegranskat)abstract
    • In situ hybridization using beta-nerve growth factor (NGF) DNA probes was used to demonstrate NGF mRNA in spermatocytes and early spermatids of adult mouse. NGF mRNA-containing cells were also identified in the epithelium of convoluted ducts in mouse corpus epididymidis. Blot-hybridization analysis of RNA prepared from mouse testis and epididymis as well as from rat epididymis confirmed the presence of a 1.3-kilobase (kb) NGF mRNA in these tissues. In the rat testis, however, only a 1.5-kb NGF mRNA was found, corresponding in size to a minor NGF mRNA detected in the rat brain, heart, and epididymis. By using affinity-purified anti-NGF antibodies, NGF-like immunoreactivity was observed in germ cells of rat and mouse testis and in the lumen of epididymis. Extracts of both mouse epididymis and testis stimulated fiber outgrowth in cultured sympathetic ganglia, and the effect was blocked by antibodies to mouse NGF. A two-site enzyme immunoassay showed the presence of 10 and 70 ng of NGF per g of tissue in the mouse testis and epididymis, respectively. Furthermore, RNA blot analysis showed the presence of mRNA for the NGF receptor in mouse testis. These results suggest a nonneurotrophic role for NGF in the male reproductive system, possibly in survival maturation and/or motility of spermatozoa.
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10.
  • Baumgartner, T., et al. (författare)
  • A survey of the European Reference Network EpiCARE on clinical practice for selected rare epilepsies
  • 2021
  • Ingår i: Epilepsia Open. - : Wiley. - 2470-9239. ; 6:1, s. 160-170
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: Clinical care of rare and complex epilepsies is challenging, because evidence-based treatment guidelines are scarce, the experience of many physicians is limited, and interdisciplinary treatment of comorbidities is required. The pathomechanisms of rare epilepsies are, however, increasingly understood, which potentially fosters novel targeted therapies. The objectives of our survey were to obtain an overview of the clinical practice in European tertiary epilepsy centers treating patients with 5 arbitrarily selected rare epilepsies and to get an estimate of potentially available patients for future studies. Methods: Members of the European Reference Network for rare and complex epilepsies (EpiCARE) were invited to participate in a web-based survey on clinical practice of patients with Dravet syndrome, tuberous sclerosis complex (TSC), autoimmune encephalitis, and progressive myoclonic epilepsies including Unverricht Lundborg and Unverricht-like diseases. A consensus-based questionnaire was generated for each disease. Results: Twenty-six of 30 invited epilepsy centers participated. Cohorts were present in most responding centers for TSC (87%), Dravet syndrome (85%), and autoimmune encephalitis (71%). Patients with TSC and Dravet syndrome represented the largest cohorts in these centers. The antiseizure drug treatments were rather consistent across the centers especially with regard to Dravet syndrome, infantile spasms in TSC, and Unverricht Lundborg / Unverricht-like disease. Available, widely used targeted therapies included everolimus in TSC and immunosuppressive therapies in autoimmune encephalitis. Screening for comorbidities was routinely done, but specific treatment protocols were lacking in most centers. Significance: The survey summarizes the current clinical practice for selected rare epilepsies in tertiary European epilepsy centers and demonstrates consistency as well as heterogeneity in the treatment, underscoring the need for controlled trials and recommendations. The survey also provides estimates for potential participants of clinical trials recruited via EpiCARE, emphasizing the great potential of Reference Networks for future studies to evaluate new targeted therapies and to identify novel biomarkers. © 2020 The Authors. Epilepsia Open published by Wiley Periodicals LLC on behalf of International League Against Epilepsy
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