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Biomedical subjects

C Ide

Publications and source records attributed to C Ide.

At least 19 recordsLinked to original sources
PubMed2000

VAMP-2 promotes neurite elongation and SNAP-25A increases neurite sprouting in PC12 cells.

Recent studies suggest that the soluble N-ethylmaleimide-sensitive factor attached protein (SNAP) receptor (SNARE)-mediated membrane fusion system is involved in vesicle fusion in the plasma membrane that allows expansion for neurite elongation. There have been several reports analyzing the effects of neurite outgrowth by inhibition of SNAREs. In this study, we took the opposite approach by overexpressing green fluorescent protein (GFP)-fusion SNAREs, including VAMP-2, SNAP-25A, and syntaxin1A, in PC12 cells to investigate the role of SNAREs in the neurite outgrowth of PC12 cells. Neurite outgrowth analysis demonstrated that: (1) GFP-VAMP-2 increased the length of individual neurites, without changing the number of neurites per cell; (2) GFP-SNAP-25A increased the number of neurites per cell, with no change in the length of the individual neurites. In both cases, the total length of neurites per cell was increased; (3) GFP-syntaxin1A resulted in no significant change, either in neurite length, or in the number of neurites per cell. These findings suggest that when overexpressed in PC12 cells, VAMP-2 can promote neurite elongation, while SNAP-25A can stimulate neurite sprouting. On the other hand, overexpression of syntaxin1A neither promotes nor inhibits neurite outgrowth. Thus VAMP-2 and SNAP-25A play different roles in neurite elongation and sprouting.

Animals↗
PubMed2000

Positron emission tomography with fluorodeoxyglucose for suspected head and neck tumor recurrence in the symptomatic patient.

OBJECTIVE: To analyze the impact of positron emission tomography with fluorodeoxyglucose (FDG-PET) in the treatment of patients suspected of having head and neck cancer recurrence. STUDY DESIGN: Prospective and consecutive inclusion of 44 patients presenting with clinical symptoms suggestive of head and neck tumor recurrence. METHODS: FDG-PET was compared with combined computed tomography (CT) plus magnetic resonance imaging (MRI) procedures for the differential diagnosis between tumor recurrence and benign post-therapeutic changes. For FDG-PET, the potential additional value of semiquantitative indexes was studied. The impact on patient treatment (i.e., their ability to accurately select patients for panendoscopic exploration) was analyzed retrospectively for both CT+MRI and PET workups. RESULTS: The diagnostic accuracy was found higher for PET than for combined CT+MRI: sensitivity ranged from 96% to 73%, specificity from 61% to 50%, and accuracy from 81% to 64% for PET and CT+MRI, respectively. The accuracy of FDG-PET was the highest (94%) in patients included more than 12 weeks after the end of therapy. In 15 discordant cases, PET was correct in 11 and CT+MRI in 4. Patient selection for panendoscopic exploration and biopsy was correct in 79% and 50% of patients with FDG-PET and CT+MRI, respectively. Quantification of FDG uptake had no additional value over visual analysis alone, although we found that a SUVlbm (standardized uptake value corrected for lean body mass) threshold of 3 could be helpful in patients scanned less than 12 weeks after the end of therapy. CONCLUSION: FDG-PET has a major additional diagnostic value to CT+MRI for the evaluation of the symptomatic patient suspected of having head and neck cancer recurrence. PET could have a direct impact on management by correctly selecting patients in whom a panendoscopic exploration with biopsy is indicated.

Adult↗
PubMed1999

Distribution of synaptosomal-associated protein 25 in nerve growth cones and reduction of neurite outgrowth by botulinum neurotoxin A without altering growth cone morphology in dorsal root ganglion neurons and PC-12 cells.

Synaptosomal-associated protein 25 has been regarded as one of the target-associated soluble N-ethylmaleimide-sensitive fusion attachment protein receptors essential for exocytosis of vesicles in synapses. We have previously reported that cleavage of syntaxin, which is another target-associated soluble N-ethylmaleimide-sensitive fusion attachment protein receptor, with botulinum neurotoxin C1 resulted in inhibition of neurite extension and morphological changes including growth cone collapse and large vacuole formation. As an attempt to explore the mechanism of growth cone extension, we examined the ultrastructural localization of synaptosomal-associated protein 25 in growth cones with or without treatment of botulinum neurotoxin A, which cleaves synaptosomal-associated protein 25. In dorsal root ganglion neurons, light microscopy demonstrated synaptosomal-associated protein 25 immunoreactivity throughout the neurons, including the cell bodies, neurites and growth cones. Using electron microscopy, gold signals immunoreactive for synaptosomal-associated protein 25 were identified diffusely in the cytoplasm of the growth cones. In contrast, in PC-12 cells, a large number of gold signals were localized on the plasma membranes. High levels of signal were also found in the cytoplasm in the central region of the growth cones. We also confirmed that botulinum neurotoxin A treatment reduced neurite extension by about 50%. However, both in dorsal root ganglion neurons and in PC-12 cells we found no differences in the ultrastructure nor in the localization of synaptosomal-associated protein 25 between growth cones with and without toxin treatment. These results indicate that cleavage of synaptosomal-associated protein 25 inhibits growth cone extension in a manner different than that of syntaxin cleavage. The results of this study suggest the possibility that synaptosomal-associated protein 25 is involved in growth cone extension through a process independent of vesicle fusion.

Animals↗
PubMed1999

Nerve regeneration through biodegradable gelatin conduits in mice.

OBJECTIVE: To test if fabricated gelatin conduits can be used to bridge nerve inter-stump gaps and support regeneration. DESIGN: Experimental laboratory study. SETTING: Department of Anatomy and Neurobiology, Graduate School of Medicine, Kyoto University, Japan. SUBJECTS: Twenty-four adult mice. INTERVENTION: Mouse's sciatic nerve was resected and both proximal and distal nerve stumps sutured into each end of a gelatin conduit, to bridge a 7-mm gap. MAIN OUTCOME MEASURES: Nerve regeneration. RESULTS: At one week post-implantation, a scaffolding fibrin matrix containing few mononuclear cells formed inside the conduit. At three weeks, a well regenerated nerve composed of myelinated and unmyelinated axons, associated Schwann cells and surrounding perineurial sheath bridged the gap. CONCLUSION: Biodegradable gelatin conduits direct and support nerve regeneration and are therefore promising tools for use in entubulization repair of nerve defects.

Animals↗
PubMed1998

Regeneration of dorsal column axons after spinal cord injury in young rats.

In contrast to previous reports denying the occurrence of axonal regeneration of the dorsal column (DC) projections, here we demonstrate for the first time that marked regeneration occurs spontaneously after transection in infant rats. Transection was made sharply so as to produce edema-free lesions without subsequent formation of either scars or cysts. Transganglionic labeling of axons revealed that regenerated axons ascended in the normal tract in a manner similar to normal projections as a tightly-packed fasciculus and terminated densely in the nucleus gracilis. The present study indicates that failure of regeneration of DC axons is due to neither intrinsic deficiency of regrowth potential nor globally-inhospitable axonal environment but rather the local conditions of the lesion site.

Animals↗
PubMed1998

Localization of tyrosine-phosphorylated proteins in cultured mouse dorsal root ganglion neurons.

The present study, using confocal laser scanning microscopy and immunoelectron microscopy, examined the intracellular localization of tyrosine-phosphorylated proteins in cultured mouse dorsal root ganglion neurons with special reference to their growth cones. The growth cone is the specialized structure formed at the growing tip of the axon; characteristically highly motile with filopodia on the surface, it is responsible for the extension and guidance of the neurites to the appropriate targets during nerve regeneration. It has been suggested that protein-tyrosine phosphorylation plays an important role in the intracellular signal transduction that regulates the extension and motility of growth cones. By fluorescence immunocytochemistry, phosphotyrosine immunoreactivity was found in the growth cones and neurites. Some of the filopodia exhibited strong immunoreactivity at their tips. By immunoelectron microscopy, a large number of immunogold particles (gold particles conjugated to the secondary antibody) were seen to be distributed in the cytoplasm and some were observed on the plasma membrane in the growth cones, whereas in the neurites the density of immunogold particles was the same in the axoplasm as on the plasma membranes. These findings suggest that in the growth cones phosphotyrosines might mainly be involved in intracellular signaling for maintaining their high motility whereas in the neurites they might mostly be associated with the receptor proteins at the plasma membrane for adhesion as well as for growth of neurites. Thus, tyrosine phosphorylation might contribute to different functions for growth cones and neurites.

Animals↗
PubMed1998

Long acellular nerve transplants for allogeneic grafting and the effects of basic fibroblast growth factor on the growth of regenerating axons in dogs: a preliminary report.

Sciatic nerves were excised from 3 beagle dogs about 5 h after their sacrifice, treated three times by freezing and thawing, and stored in physiological saline for 3 months at -20 degrees C until used. Nerve segments 5 cm in length prepared from these stored nerves were transplanted to the common peroneal nerve in the right hindlimb of beagle dogs. Sixteen beagle dogs in total were used, in four treatment groups of two pairs each studied at 1 and 3 months. Five-hundred microliters basic fibroblast growth factor (bFGF) of two different concentrations (10 micrograms/300 microliters and 100 micrograms/300 microliters) which were impregnated in 0.5 ml gelatin hydrogels was applied around the sutured allografts. Autografting was also done in 4 beagle dogs, with no bFGF application. One month after the grafting, no regenerating nerves extended beyond the middle of the transplant in any of the allografts, except in the autografts in which a number of regenerated (myelinated) axons were present. Three months after the grafting, an abundance of myelinated axons was found at the middle of the graft: the numbers of axons per 10(4) micron 2 were 22.6 in the autografts and 10.6, 10.4 and 19.2 in the allografts treated with no bFGF, low-dose bFGF, and high-dose bFGF, respectively. Regenerating axons extended into the host nerve: the numbers of myelinated axons at the level 1.5 cm distal to the distal suture were 35.7, 0.9, 3.8, and 12.1 per 10(4) micron 2 in the above respective order. Although it was inferior in quality to the autograft, peripheral nerve regeneration was extensive in the distal nerve using freeze-thawed and bFGF-treated allografts at 3 months. Electromyography showed that the peroneus longus muscle responded to the electrical stimuli given at the site proximal to the transplant in all four groups. These data indicate that a 5-cm acellular nerve segment containing Schwann cell basal laminae can be used successfully as an allograft without any immunosuppressants and that exogenously applied bFGF can improve nerve regeneration by enhancing the growth of regenerating axons.

Animals↗
PubMed1998

Effects of prelesioned peripheral nerve graft on nerve regeneration in the rat spinal cord.

OBJECTIVE: The aim of this study was to examine the effects of prelesioned peripheral nerve grafts on central nerve regeneration compared with the freshly transected peripheral nerve grafts in the dorsal funiculus of the rat spinal cord. METHODS: The experimental paradigm consisted of ligating the common peroneal nerve at the midthigh level for 7 days, while the adjacent tibial nerve was left intact. Numerous Schwann cells appeared accompanying regenerating axons in the proximal stump of the ligated nerve. The proximal stumps of the ligated (prelesioned) common peroneal nerve and the intact (untreated) tibial nerve were excised as one tissue block and autografted into the dorsal funiculi of the upper cervical cord. The graft was placed so that the prelesioned common peroneal nerve was positioned on the left dorsal funiculus and the untreated tibial nerve was positioned to the right of the midsagittal plane. Nerve regeneration was examined by light and transmission electron microscopy 1 to 16 weeks after grafting, comparing the effectiveness of prelesioned and untreated nerve grafts. RESULTS: Numerous regenerating axons were observed in the caudal border of both grafts 1 to 2 weeks after grafting. Astrocyte proliferation was suppressed in the prelesioned grafts compared to the untreated grafts. Four to 16 weeks later, the number of regenerating axons was approximately 10-fold as large in the prelesioned grafts as in the untreated grafts. The regenerating axons were myelinated by Schwann cells. Astrocytic glial scar formation was inconspicuous in the prelesioned grafts, whereas it was prominent in the untreated grafts. Schwann cells were contiguous with astrocytes along regenerating axons, forming a continuous conduit from the central to peripheral nerve microenvironments for the outgrowth of regenerating axons. CONCLUSION: The prelesioned peripheral nerve graft is more effective than the untreated graft in suppressing astrocytic scar formation and in supporting the outgrowth of regenerating axons in the dorsal funiculus of rat spinal cord.

Animals↗
PubMed1998

Unusual occipitoatlantal fracture dissociation with no neurological impairment. Case report.

The authors describe an unusual case of a complex traumatic fracture-dissociation injury of the craniovertebral junction, which the patient survived with no neurological damage. This case featured the rare combination of an avulsion of both the right occipital condyle and clivus and a fracture of the left lateral mass of the atlas. Because of the craniocervical ligament injury and the slight anterior occipitoatlantal dislocation, the lesion was considered to be unstable and was treated successfully with a cervical collar. The authors emphasize that thin-slice computerized tomography scanning with multiplanar reconstructions is essential to visualize these fractures, whereas magnetic resonance imaging is useful to assess soft tissues.

Adult↗
PubMed1998

An early MR observation of carotid involvement by retropharyngeal abscess.

We report early carotid involvement by retropharyngeal abscess in a 4-year-old boy. MR imaging showed enhancement of the wall and narrowing of the lumen of the internal carotid artery, which were thought to reflect spasm and/or arteritis. Prompt treatment may have prevented hemorrhagic and neurologic complications.

Carotid Arteries↗
PubMed1997

The Ras target AF-6 interacts with ZO-1 and serves as a peripheral component of tight junctions in epithelial cells.

The dynamic rearrangement of cell-cell junctions such as tight junctions and adherens junctions is a critical step in various cellular processes, including establishment of epithelial cell polarity and developmental patterning. Tight junctions are mediated by molecules such as occludin and its associated ZO-1 and ZO-2, and adherens junctions are mediated by adhesion molecules such as cadherin and its associated catenins. The transformation of epithelial cells by activated Ras results in the perturbation of cell-cell contacts. We previously identified the ALL-1 fusion partner from chromosome 6 (AF-6) as a Ras target. AF-6 has the PDZ domain, which is thought to localize AF-6 at the specialized sites of plasma membranes such as cell-cell contact sites. We investigated roles of Ras and AF-6 in the regulation of cell-cell contacts and found that AF-6 accumulated at the cell-cell contact sites of polarized MDCKII epithelial cells and had a distribution similar to that of ZO-1 but somewhat different from those of catenins. Immunoelectron microscopy revealed a close association between AF-6 and ZO-1 at the tight junctions of MDCKII cells. Native and recombinant AF-6 interacted with ZO-1 in vitro. ZO-1 interacted with the Ras-binding domain of AF-6, and this interaction was inhibited by activated Ras. AF-6 accumulated with ZO-1 at the cell-cell contact sites in cells lacking tight junctions such as Rat1 fibroblasts and PC12 rat pheochromocytoma cells. The overexpression of activated Ras in Rat1 cells resulted in the perturbation of cell-cell contacts, followed by a decrease of the accumulation of AF-6 and ZO-1 at the cell surface. These results indicate that AF-6 serves as one of the peripheral components of tight junctions in epithelial cells and cell-cell adhesions in nonepithelial cells, and that AF-6 may participate in the regulation of cell-cell contacts, including tight junctions, via direct interaction with ZO-1 downstream of Ras.

Animals↗
PubMed1997

Nedd5, a mammalian septin, is a novel cytoskeletal component interacting with actin-based structures.

The mouse Nedd5 gene encodes a 41.5-kD GTPase similar to the Saccharomyces and Drosophila septins essential for cytokinesis. Nedd5 accumulates near the contractile ring from anaphase through telophase, and finally condenses into the midbody. Microinjection of anti-Nedd5 antibody interferes with cytokinesis, giving rise to binucleated cells. In interphase and postmitotic cells, Nedd5 localizes to fibrous or granular structures depending on the growth state of the cell. The Nedd5-containing fibers are disrupted by microinjection of GTPgammaS and by Nedd5 mutants lacking GTP-binding activity, implying that GTP hydrolysis is required for its assembly. The Nedd5-containing fibers also appear to physically contact actin bundles and focal adhesion complexes and are disrupted by cytochalasin D, C3 exoenzyme, and serum starvation, suggesting a functional interaction with the actin-based cytoskeletal systems in interphase cells.

3T3 Cells↗
PubMed1997

Castleman's disease in the neck: MRI.

We describe a case of Castleman's disease in a 8-year-old-boy who presented with a slowly growing mass in the upper neck. MRI showed a well-defined homogeneous mass with nonspecific signal features. Unusual features were a kidney-bean shape and the deep location in the suprahyoid region, the mass originating in the left retropharyngeal space.

Biopsy↗
PubMed1997

Developmental changes in the subcellular localization of R-cadherin in chick retinal pigment epithelium.

It has been reported that in the chick embryonic retina, N-cadherin first appears at the very early stages and is subsequently substituted by R-cadherin at the middle to late stages of development. To examine the role of R-cadherin in the morphogenesis of chick retinal pigment epithelium (RPE), the distribution of this adhesion molecule was studied by immunofluorescence cytochemistry and immunoelectron microscopy from embryonic day (E) 6 to hatching. R-cadherin immunoreactivity was detected at E6, and was strongest at E12-13. During these stages, R-cadherin was expressed uniformly on the lateral plasma membranes of RPE cells in contact with each other. Thereafter, R-cadherin immunoreactivity was markedly decreased, with intense immunoreactivity restricted to zonulae adherentes in latero-apical regions at E16. R-cadherin immunoreactivity was no longer detectable in the newly hatched chick RPE, even though morphologically well developed zonulae adherentes were present in latero-apical regions. No immunoreactivity was detected on the apical side facing the neural retina or on the basal side facing the basal lamina at any stage of development. These findings indicate that R-cadherin plays an important role as a major cadherin subtype in the morphogenesis of chick embryo RPE, and is involved initially in non-specific cell-cell adhesions, and subsequently in the formation and maintenance of developing zonulae adherentes.

Animals↗
PubMed1997

Experimental syringomyelia: late ultrastructural changes of spinal cord tissue and magnetic resonance imaging evaluation.

BACKGROUND: In human hydrosyringomyelia and in the late stage of experimental syringomyelia, the spinal cord tissue adjacent to the syrinx is exposed to a similar pathophysiologic condition. We investigated the ultrastructural changes in the late stages of kaolin-induced syringomyelia, and in addition, we presented magnetic resonance imaging (MRI) findings of the cervicomedullary junction and syrinx, and the nature of edema in the spinal cord of this experimental model. METHODS: Syringomyelia was induced in rabbits by intracisternal injection of kaolin. MRI was performed at 6 weeks, and 6 and 12 months following injection, and the animals were killed by transcardial perfusion of formaldehyde solution and examined by transmission electron microscopy. Evans blue was injected intravenously in six rabbits, 6 weeks and 12 months following kaolin injection and was examined by confocal laser scanning microscopy. RESULTS: MRI showed that the syrinx communicated with the fourth ventricle in most animals. Demyelination of varying degrees and slight edematous change were seen in the perisyrinx white matter. No extravasation of Evans blue was seen by confocal microscopy. Abundant astrocytic proliferation with a large number of glial filaments was seen at the margin of the syrinx and between the axons in the perisyringeal region. The perivascular space enlargement occurred in both the gray and white matter. The endothelial junctions appeared intact. Regenerating axons and remyelination by oligodendrocytes were seen occasionally. CONCLUSIONS: The MRI confirmed the communication between the fourth ventricle and the syrinx. The ultrastructural changes were almost identical to those of the early stage syrinx, but the astrocytic proliferation was more severe, and the edema was less in the late stage. The perisyrinx edema appeared to be of the interstitial type, as in hydrocephalus. Axonal degeneration and demyelination continued with abortive attempt at regeneration and remyelination in the less edematous late stage, which might be the cellular basis for the persistence or worsening of clinical symptoms and signs in the chronic stage of syringomyelia even after surgical treatment.

Animals↗