Posttranslational modification of a neurofilament protein during axoplasmic transport: implications for regional specialization of CNS axons

The possibility that proteins are modified during axoplasmic transport in central nervous system axons was examined by analyzing neurofilament proteins (200,000, 140,000, and 70,000 mol wt) along the mouse primary optic pathway (optic nerve and optic tract). The major neurofilament proteins (NFPs) exhibited considerable microheterogeneity. At least three forms of the “ 140,000” neurofilament protein differing in molecular weight by SDS PAGE (140,000-145,000 mol wt) were identified. The “140,000” proteins, and their counterparts in purified neurofilament preparations, displayed similar isoelectric points and the same peptide maps. The “140,000” NFPs exhibited regional heterogeneity when consecutive segments of the optic pathway were separately examined on polyacrylamide gels. Two major species (145,000 and 140,000 mol wt) were present along the entire length of the optic pathway. The third protein (143,000 mol wt) was absent proximally but became increasingly prominent in distal segments. After intravitreal injection of [(3)H]proline, newly synthesized radiolabeled proteins in the “140,000” mol wt region entered proximal mouse retinal ganglion cell (RGC) axons as two major species corresponding to the 145,000 and 14,000 mol wt NFPs observed on stained gels. When transported NFPs reached more distal axonal regions (30 d postinjection or longer), a 143,000 mol wt protein appeared that was similar in isoelectric point and peptide map to the 145,000 and 140,000 mol wt species. The results suggest that (a) the composition of CNS neurofilaments, particularly the “140,000” component, is more complex than previously recognized, that (b) retinal ganglion cell axons display regional differentiation with respect to these cytoskeletal proteins, and that (c) structural heterogeneity of “140,000” NFPs arises, at least in part, from posttranslational modification during axoplasmic transport. When excised but intact optic pathways were incubated in vitro at pH 7.4, a 143,000 NFP was rapidly formed by a calcium-dependent enzymatic process active at endogenous calcium levels. Changes in major proteins other than those in the 145,000-140,000 mol wt region were minimal. In optic pathways from mice injected intravitreally with L-[(3)H]proline, tritiated 143,000 mol wt NFP formed rapidly in vitro if radioactively labeled NFPs were present in distal RGC axonal regions (31 d postinjection). By contrast, no 143,000 mol wt NFP was generated if radioactively labeled NFPs were present proximally in RGC axons (6 d postinjection). The enzymatic process that generates 143,000 mol wt NFP in vitro, therefore, appears to have a nonuniform distribution along the RGC axons. The foregoing results and other observations, including the accompanying report (J. Cell Biol., 1982, 94:159-164), imply that CNS axons may be regionally specialized with respect to structure and function

When What's Left Is Right: Visuomotor Transformations in an Aged Population

Background: There has been little consensus as to whether age-related visuomotor adaptation effects are readily observable. Some studies have found slower adaptation, and/or reduced overall levels. In contrast, other methodologically similar studies have found no such evidence of aging effects on visuomotor adaptation. A crucial early step in successful adaptation is the ability to perform the necessary transformation to complete the task at hand. The present study describes the use of a viewing window paradigm to examine the effects of aging in a visuomotor transformation task. Methods: Two groups of participants, a young adult control group (age range 18–33 years old, mean age = 22) and an older adult group (age range 62–74, mean age = 68) completed a viewing window task that was controlled by the user via a computer touchscreen. Four visuomotor ‘‘flip’ ’ conditions were created by varying the relationship between the participant’s movement, and the resultant on-screen movement of the viewing window: 1) No flip 2) X-Axis and Y-axis body movements resulted in the opposite direction of movement of the viewing window. In each of the 3) Flip-X and 4) Flip-Y conditions, the solitary X- or Y-axes were reversed. Response times and movement of the window were recorded. Conclusions: Older participants demonstrated impairments in performing a required visuomotor transformation, as evidenced by more complex scanning patterns and longer scanning times when compared to younger control participants. These results provide additional evidence that the mechanisms involved in visuomotor transformation are negatively affected by age

Enhanced catecholamine transporter binding in the locus coeruleus of patients with early Parkinson disease

<p>Abstract</p> <p>Background</p> <p>Studies in animals suggest that the noradrenergic system arising from the locus coeruleus (LC) and dopaminergic pathways mutually influence each other. Little is known however, about the functional state of the LC in patients with Parkinson disease (PD).</p> <p>Methods</p> <p>We retrospectively reviewed clinical and imaging data of 94 subjects with PD at an early clinical stage (Hoehn and Yahr stage 1-2) who underwent single photon computed tomography imaging with FP-CIT ([¹²³I] N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) tropane). FP-CIT binding values from the patients were compared with 15 healthy subjects: using both a voxel-based whole brain analysis and a volume of interest analysis of <it>a priori </it>defined brain regions.</p> <p>Results</p> <p>Average FP-CIT binding in the putamen and caudate nucleus was significantly reduced in PD subjects (43% and 57% on average, respectively; p < 0.001). In contrast, subjects with PD showed an increased binding in the LC (166% on average; p < 0.001) in both analyses. LC-binding correlated negatively with striatal FP-CIT binding values (caudate: contralateral, ρ = -0.28, p < 0.01 and ipsilateral ρ = -0.26, p < 0.01; putamen: contralateral, ρ = -0.29, p < 0.01 and ipsilateral ρ = -0.29, p < 0.01).</p> <p>Conclusions</p> <p>These findings are consistent with an up-regulation of noradrenaline reuptake in the LC area of patients with early stage PD, compatible with enhanced noradrenaline release, and a compensating activity for degeneration of dopaminergic nigrostriatal projections.</p

Single-level anterior cervical discectomy and interbody fusion using PEEK anatomical cervical cage and allograft bone

BACKGROUND: In an effort to avoid the morbidity associated with autogenous bone graft harvesting, cervical cages in combination with allograft bone are used to achieve fusion. The goal of the current study was to assess the reliability and efficacy of anterior cervical discectomy and interbody fusion (ACDF) using a PEEK anatomical cervical cage in the treatment of patients affected by single-level cervical degenerative disease. METHODS AND MATERIALS: Twenty-five patients affected by single-level cervical degenerative pathology between C4 and C7 were enrolled in this study. The clinical findings were assessed using the Neck Disability Index and the Visual Analog Scale. Surgical outcomes were rated according to Odom's criteria at last follow-up. Fusion was graded as poor, average, good or excellent by assessing the radiographs. Cervical spine alignment was evaluated by sagittal segmental alignment and sagittal alignment of the whole cervical spine preoperatively, 6 months postoperatively and at the last follow-up. RESULTS: Twenty-five patients underwent ACDF using a PEEK anatomical cervical cage. All patients had a minimum 2 years of follow-up. The operative levels were C4-C5 in 5 patients, C5-C6 in 12 patients and C6-C7 in 8 patients. Preoperatively, average NDI was 34, 13 at 6 months, and 10 at latest follow-up. The mean preoperative VAS was 7; the mean postoperative VAS at latest follow-up was 3. Good or excellent fusion was achieved in all patients within 10 months (mean 5 months). Preoperatively, average sagittal segmental alignment (SSA) was 0.2\ub0 and average sagittal alignment of the cervical spine (SACS) 15.8\ub0. Six months after surgery, average SSA was 1.8\ub0 and average SACS 20.9\ub0, and at last follow-up, average SSA was 1.6\ub0 and average SACS 18.5\ub0. CONCLUSION: Anterior cervical discectomy and interbody fusion using PEEK anatomical cervical cages can be considered a safe and effective technique to cure cervical disc herniation with intractable pain or neural deficit in cases where conservative treatment failed

Gene Expression Profiling in Limb-Girdle Muscular Dystrophy 2A

Limb-girdle muscular dystrophy type 2A (LGMD2A) is a recessive genetic disorder caused by mutations in calpain 3 (CAPN3). Calpain 3 plays different roles in muscular cells, but little is known about its functions or in vivo substrates. The aim of this study was to identify the genes showing an altered expression in LGMD2A patients and the possible pathways they are implicated in. Ten muscle samples from LGMD2A patients with in which molecular diagnosis was ascertained were investigated using array technology to analyze gene expression profiling as compared to ten normal muscle samples. Upregulated genes were mostly those related to extracellular matrix (different collagens), cell adhesion (fibronectin), muscle development (myosins and melusin) and signal transduction. It is therefore suggested that different proteins located or participating in the costameric region are implicated in processes regulated by calpain 3 during skeletal muscle development. Genes participating in the ubiquitin proteasome degradation pathway were found to be deregulated in LGMD2A patients, suggesting that regulation of this pathway may be under the control of calpain 3 activity. As frizzled-related protein (FRZB) is upregulated in LGMD2A muscle samples, it could be hypothesized that β-catenin regulation is also altered at the Wnt signaling pathway, leading to an incorrect myogenesis. Conversely, expression of most transcription factor genes was downregulated (MYC, FOS and EGR1). Finally, the upregulation of IL-32 and immunoglobulin genes may induce the eosinophil chemoattraction explaining the inflammatory findings observed in presymptomatic stages. The obtained results try to shed some light on identification of novel therapeutic targets for limb-girdle muscular dystrophies