| 551. |
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| 552. |
- Nissan, Tracy A, et al.
(author)
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60S pre-ribosome formation viewed from assembly in the nucleolus until export to the cytoplasm
- 2002
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In: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 21:20, s. 5539-5547
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Journal article (peer-reviewed)abstract
- 60S ribosomes undergo initial assembly in the nucleolus before export to the cytoplasm and recent analyses have identified several nucleolar pre-60S particles. To unravel the steps in the pathway of ribosome formation, we have purified the pre-60S ribosomes associated with proteins predicted to act at different stages as the pre-ribosomes transit from the nucleolus through the nucleoplasm and are then exported to the cytoplasm for final maturation. About 50 non-ribosomal proteins are associated with the early nucleolar pre-60S ribosomes. During subsequent maturation and transport to the nucleoplasm, many of these factors are removed, while others remain attached and additional factors transiently associate. When the 60S precursor particles are close to exit from the nucleus they associate with at least two export factors, Nmd3 and Mtr2. As the 60S pre-ribosome reaches the cytoplasm, almost all of the factors are dissociated. These data provide an initial biochemical map of 60S ribosomal subunit formation on its path from the nucleolus to the cytoplasm.
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| 553. |
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| 554. |
- Nordin, Steven, 1960-, et al.
(author)
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Applicability of the Scandinavian odor identification test : a Finnish–Swedish comparison
- 2002
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In: Acta Oto-Laryngologica. - : Taylor & Francis. - 0001-6489 .- 1651-2251. ; 122:3, s. 294-297
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Journal article (peer-reviewed)abstract
- The possibility of using the Scandinavian Odor Identification Test (SOIT), developed for clinical purposes for use with Swedish subjects, for assessment of another northern European population was studied by comparing test performance between 127 Finnish and 127 Swedish participants, who were matched for age (19-85 years) and gender. The results showed very similar performance between countries and demonstrated, as expected, age- and gender-related differences in performance. Test-retest reliability was as good in Finnish as in Swedish subgroups of participants and no significant difference between countries in terms of diagnostic distribution (normosmia, hyposmia and anosmia) was found when using existing cut-off scores. The findings suggest that the SOIT, with its diagnostic cut-off scores, is reliable and valid for use with Finnish populations.
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| 555. |
- Nordlund, Annika, 1969-, et al.
(author)
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Value structures behind pro-environmental behavior
- 2002
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In: Environment and Behavior. - : Sage Publications. - 0013-9165 .- 1552-390X. ; 34:6, s. 740-756
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Journal article (peer-reviewed)abstract
- The purpose of the study was to test a hierarchical model of the effects of general values, environmental values, problem awareness, and personal norms on general proenvironmental behavior. The model starts with the effects of the relatively stable structures of general values and moves toward effects of more specific environmental values, environmental problem awareness, and personal norms. A personal norm was expected to mediate the effects of values and problem awareness on proenvironmental behavior. Survey data from a Swedish sample of 1,400 individuals were used in a path analysis to test the model, which was supported, and the results showed that the personal norm could be seen as derived from self-transcendent and ecocentric values and activated by problem awareness. The personal norm mediated the effects from general values, environmental values, and problem awareness on proenvironmental behavior.
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| 556. |
- Nordström, Ulrika, et al.
(author)
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Progressive induction of caudal neural character by graded Wnt signaling
- 2002
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In: Nature Neuroscience. - : Nature Publishing Group. - 1097-6256 .- 1546-1726. ; 5:6, s. 525-532
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Journal article (peer-reviewed)abstract
- Early in differentiation, all neural cells have a rostral character. Only later do posteriorly positioned neural cells acquire characteristics of caudal forebrain, midbrain and hindbrain cells. Caudalization of neural tissue in the chick embryo apparently involves the convergent actions of (i) fibroblast growth factor (FGF) signaling and (ii) signaling from the caudal paraxial mesoderm, or 'PMC activity', which has not yet been defined molecularly. Here we report evidence that Wnt signaling underlies PMC activity, and show that Wnt signals act directly and in a graded manner on anterior neural cells to induce their progressive differentiation into caudal forebrain, midbrain and hindbrain cells.
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| 557. |
- Norgren, Niklas, et al.
(author)
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Monoclonal antibodies selective for low molecular weight neurofilaments
- 2002
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In: Hybridoma and Hybridomics. - : Mary Ann Liebert Inc. - 1536-8599. ; 21:1, s. 53-59
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Journal article (peer-reviewed)abstract
- Neurofilaments are necessary for the maintenance of axonal caliber and structural organization of nerve cells. The low molecular weight form of neurofilament, the neurofilament light protein, which serves as the core of the filament, was used as immunogen for generation of hybridomas with selective reactivity with this form of the filament. Six hybridomas, out of approximately 100 tested clones, were highly discriminatory. All involved epitopes were localized to the rod region of the antigen, as determined by alpha-chymotrypsin digestion of the purified filament and enzymatic peptide mapping. Synthetic peptides (20 mers) covering the entire rod region did not react with the antibodies. A phage display peptide library was used to identify four consensus sequences for the antibodies. The results indicate that all epitopes were of conformational type. Pair-wise BIAcore data furthermore indicated that the epitopes were independent. The access to such specific reagents is a prerequisite for further elucidation of the biology of the low molecular weight form of neurofilaments proteins.
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| 558. |
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| 559. |
- Novikov, Lev N, et al.
(author)
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A novel biodegradable implant for neuronal rescue and regeneration after spinal cord injury.
- 2002
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In: Biomaterials. - 0142-9612 .- 1878-5905. ; 23:16, s. 3369-76
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Journal article (peer-reviewed)abstract
- After spinal cord injury, the severed neuronal pathways fail to regenerate spontaneously. This study describes a biodegradable implant using poly-beta-hydroxybutyrate (PHB) fibers as carrier scaffold for matrix components and cell lines supporting neuronal survival and regeneration after spinal cord injury. After cervical spinal cord injury in adult rats, a graft consisting of PHB fibers coated with alginate hydrogel + fibronectin was implanted in the lesion cavity. In control groups, PHB was omitted and only alginate hydrogel or fibronectin, or their combination, were used for grafting. In addition, comparisons were made with animals treated intrathecally after spinal cord injury with the neurotrophic factors BDNF or NT-3. The neurons of the rubrospinal tract served as experimental model. In untreated animals, 45% of the injured rubrospinal neurons were lost at 8 weeks postoperatively. Implantation of the PHB graft reduced this cell loss by 50%, a rescuing effect similar to that obtained after treatment with BDNF or NT-3. In the absence of PHB support, implants of only alginate hydrogel or fibronectin, or their combination, had no effect on neuronal survival. After addition of neonatal Schwann cells to the PHB graft, regenerating axons were seen to enter the graft from both ends and to extend along its entire length. These results show that implants using PHB as carrier scaffold and containing alginate hydrogel, fibronectin and Schwann cells can support neuronal survival and regeneration after spinal cord injury
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| 560. |
- Novikova, Liudmila N, et al.
(author)
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Differential effects of neurotrophins on neuronal survival and axonal regeneration after spinal cord injury in adult rats.
- 2002
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In: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 452:3, s. 255-63
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Journal article (peer-reviewed)abstract
- Spinal cord injury (SCI) induces retrograde cell death in descending pathways, which can be prevented by long-term intrathecal infusion of neurotrophins (Novikova et al. [2000] Eur J Neurosci 12:776-780). The present study investigates whether the same treatment also leads to improved regeneration of the injured tracts. After cervical SCI in adult rats, a peripheral nerve graft was attached to the rostral wall of the lesion cavity. The animals were treated by local application into the cavity of Gelfoam soaked in (1) phosphate buffered saline (untreated controls) or (2) a mixture of the neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) (local treatment), or by intrathecal infusion of BDNF + NT-3 for (3) 2 weeks (short-term treatment) or (4) 5-8 weeks (long-term treatment). Despite a very strong survival effect, long-term treatment failed to stimulate ingrowth of descending tracts into the nerve graft. In comparison with untreated controls, the latter treatment also caused 35% reduction in axonal sprouting of descending pathways rostral to the lesion site and 72% reduction in the number of spinal cord neurons extending axons into the nerve graft. Local and short-term treatments neither prevented retrograde cell death nor enhanced regeneration of descending tracts, but induced robust regeneration of spinal cord neurons into the nerve graft. These results indicate that the signal pathways promoting neuronal survival and axonal regeneration, respectively, in descending tracts after SCI respond differently to neurotrophic stimuli and that efficient rescue of axotomized tract neurons is not a sufficient prerequisite for regeneration.
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