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At least 739 records · Page 41Linked to original sources
PubMed2003

Enhanced peripheral nerve regeneration elicited by cell-mediated events delivered via a bioresorbable PLGA guide.

Using an established rat peripheral-nerve regeneration model, the authors have demonstrated enhancement of regeneration following subcutaneous priming of bioresorbable poly(lactic-co-glycolic)acid (PLGA) guides in vivo. Four weeks after nerve reconstruction, regeneration of the peripheral nerve through the cell-infiltrated guides displayed a significant increase in the total axon number and myelination status recorded in primed over unprimed guides, demonstrating the importance of cell-mediated events in the regeneration process. To define the different components enhancing nerve regeneration in this model, they have focused on identifying factors capable of eliciting Schwann-cell migration, since this has been identified as an early and necessary event in nerve regeneration. Using an in vitro migration assay, screening of a limited number of cellular and extracellular factors has demonstrated differential promotion of Schwann-cell migration. Of interest, combining fibronectin and bFGF resulted in a two-fold enhancement in Schwann-cell migration over that recorded with either alone. These results describe a rapid screening process for identifying various molecules and combinations thereof, with potential involvement in Schwann-cell migration. Coupling these findings to the use of the PLGA guide as an in vivo delivery system provides a rationale for the selection of exogenous factors to test for the enhancement of peripheral-nerve regeneration.

Animals↗
PubMed1983

Ultrastructural study of peripheral nerve in arteritic diabetic patients.

The peripheral nerve was taken from 25 diabetic patients with arteritis just before or after amputation of a leg. The ultrastructural study of myelinated fibers showed several alterations. Loss of fibers varied greatly from case to case. This was accompanied in some cases by hypertrophy of the Schwann cells around demyelinated fibers as has been observed in some ordinary diabetic neuropathies. Unusual abnormalities consisted of particular axonal degeneration and evidence of aberrant remyelination. This axonal injury was peculiar because of the accumulation of organelles which tended to transform some of the fibers into enlarged axons. Such a lesion might correspond to a hypoxic axonopathy.

Aged↗
PubMed2006

Intraoperative somatosensory evoked potentials to facilitate peripheral nerve release.

PURPOSE: The significance of intraoperative somatosensory evoked potentials (SSEP) monitoring is well known during spinal surgery. This technology could be beneficial during peripheral nerve surgery as well. In order to illustrate potential applications, two cases of successful peripheral nerve release demonstrated by on-line, intraoperative, SSEP are reported. Clinical and technical features: The first case presents a complex brachial plexus lesion involving two mixed sensory-motor nerves: median and ulnar. The second case involved an entrapment neuropathy of the lateral femoral cutaneous nerve, a pure sensory nerve (meralgia paresthetica). For each patient we elicited specific peripheral nerve SSEP (recorded using bipolar cephalic montage) by stimulating each nerve independently. In each case, during difficult nerve dissection and after having excluded other possible factors of intraoperative SSEP variations, an increase of the SSEP amplitude was observed, and later correlated with favourable patient clinical outcome. CONCLUSIONS: Two cases demonstrate that intraoperative SSEP monitoring may provide an effective tool to guide surgical dissection during peripheral nerve release. This technique has potentially beneficial clinical applications and warrants further investigation.

Adult↗
PubMed2003

Peripheral nerve injury alters excitatory synaptic transmission in lamina II of the rat dorsal horn.

Using the blind whole cell patch-clamp recording technique, we investigated peripheral nerve injury-induced changes in excitatory synaptic transmission to neurones in lamina II of the dorsal horn. Partial (i.e. chronic constriction injury (CCI) and spared nerve injury (SNI)) and complete (i.e. sciatic nerve transection (SNT)) peripheral nerve injury altered the mean threshold intensity for eliciting A fibre-mediated EPSCs in lamina II neurones. Following SNT and CCI, EPSC threshold was significantly decreased, but following SNI, EPSC threshold was increased (naive: 32 +/- 2 mu A, SNT: 22 +/- 2 mu A, CCI: 23 +/- 2 mu A, SNI: 49 +/- 4 mu A; P < 0.01, Student's unpaired t test). Despite this disparity between models, dorsal root compound action potential recordings revealed no significant difference in the conduction velocity or activation threshold of A beta and A delta fibres in naive, SNT, CCI and SNI rats. In addition to the changes in EPSC threshold, we also observed a shift in the distribution of EPSCs. In spinal cord slices from naive rats, polysynaptic A beta fibre-evoked EPSCs were observed in 24 % of lamina II neurones, monosynaptic A delta fibre EPSCs were observed in 34 % and polysynaptic A delta fibre EPSCs were observed in 7 %. Following SNT and CCI, the percentage of neurones with polysynaptic A beta fibre EPSCs increased to > or = 65 % of the sampled population, while the percentage of neurones with monosynaptic A delta fibre EPSCs decreased to < 10 %. The percentage of neurones with polysynaptic A delta fibre EPSCs was unchanged. In contrast, following SNI, A beta fibre EPSCs decreased in incidence while the percentage of neurones with polysynaptic A delta fibre EPSCs increased to 44 %. Similar to the other injury models, however, monosynaptic A delta fibre EPSCs decreased in frequency following SNI. Thus, excitatory synaptic transmission is subject to divergent plasticity in different peripheral nerve injury models, reflecting the complexity of responses to different forms of deafferentation.

Action Potentials↗
PubMed2005

[Chitin biological tube bridging the peripheral nerve with a small gap].

OBJECTIVE: To investigate the possibility of bridging small peripheral nerve gap using a de-acetyl chitosan conduit. METHODS: The sciatic nerves of right sides were cut at SD rats. They were divided into 5 Groups randomly; Group A: epineurium suture in situ (n = 24); Group B: biological conduit with a small gap for bridging the peripheral nerve (n = 24, with 5 mm gap); Group C: epineurium suture with distal stump rotated 180 degrees (n = 24); Group D: bridging the nerve by biological conduits with a small gap, but the distal stump rotated 180 degrees (n = 24, with 5 mm gap); Group E: biological conduit with a small gap for bridging the peripheral nerve with NGF (n = 24). Electrophysiological examination, histological examination and myelinated axon counting were applied after 2, 4, 6, 8 weeks after operation respectively. RESULTS: Regenerated nerve fibers were seen in the distal nerve segments of all 5 groups; The nerve conduction velocity of small gap group (group B, D) was faster than that of corresponding simple epineurium suture group (group A, C) at all 2, 4, 6, 8 week time point (P < 0.05). The myelinated axon counting of small gap group (group B, D) was faster than that of corresponding simple epineurium suture group (group A, C) at all 4, 6, 8 week time point (P < 0.01), and there was no statistically significant difference at 2 week time point. CONCLUSION: The repair effects of chitin conduit bridging peripheral nerve with small gap (5 mm) are better than that of epineurium suture directly, and possess the potential to substitute the epineurium suture.

Animals↗
PubMed2001

Results of peripheral nerve reconstruction by autograft.

OBJECTIVES: This paper presents the results achieved in microtechnique surgeries performed during a 15-year-long period (1985-1999). By performing surgeries on 60 patients, 63 nerves were treated. MATERIAL AND METHODS: In 42 patients with injuries of peripheral nerves of upper extremities, 45 nerves were reconstructed by autografts. 14 patients were subjected to reconstructive surgeries on peripheral nerves of lower extremities. In 4 patients we reconstructed the facial nerve by means of autograft. The analysis of surgical effects has been made in dependence on indicators as follows: period elapsed from injury to surgery, age of patient, nature of injury, length of autograft, location of injury, kind of nerve inflicted. RESULTS: When assessing the results of reconstructive surgeries of peripheral nerves of lower and upper extremities we observed a big difference on the behalf of upper extremities. High efficiency can be seen in tibial nerve surgeries of lower extremities. In general we achieved good results in facial nerve reconstructions. CONCLUSION: The crucial factor that has an impact on the result of surgery is that of the time which elapsed from injury to reconstructive surgery. The factor is especially marked in younger patients. (Tab. 7, Ref. 15.).

Adult↗
PubMed2004

[Epithelioid malignant peripheral nerve sheath tumor. A case report].

Malignant peripheral nerve sheath tumors (MPNST) are exceptional and painful. The typical localization along a peripheral nerve is not always present. Prognosis is very poor. Diagnosis is particularly difficult because of the variable pathological presentation and unpredictable differentiation. We report an exceptional case of epithelioid differentiation in a 43-Year-old patient who complained of right thoracic pain for one and a half Years. Physical examination revealed weight loss and a paravertebral mass under the scapula. The chest x-ray showed a suprahilar opacity suggestive of parietal involvement and lysis of the sixth rib. Surgical biopsy of the parietal mass led to the diagnosis of epithelioid MPNST.

Adult↗
PubMed1996

Long-term results of peripheral nerve stimulation for reflex sympathetic dystrophy.

This prospective, consecutive series describes peripheral nerve stimulation (PNS) for treatment of severe reflex sympathetic dystrophy (RSD) or complex regional pain syndrome, in patients with symptoms entirely or mainly in the distribution of one major peripheral nerve. Plate-type electrodes were placed surgically on affected nerves and tested for 2 to 4 days. Programmable generators were implanted if 50% or more pain reduction and objective improvement in physical changes were achieved. Patients were followed for 2 to 4 years and a disinterested third-party interviewer performed final patient evaluations. Of 32 patients tested, 30 (94%) underwent permanent PNS placement. Long-term good or fair relief was experienced in 19 (63%) of 30 patients. In successfully treated patients, allodynic and spontaneous pain was reduced on a scale of 10 from 8.3 +/- 0.3 preimplantation to 3.5 +/- 0.4 (mean +/- standard error of the mean) at latest follow up (p<0.001). Changes in vasomotor tone and patient activity levels were markedly improved but motor weakness and trophic changes showed less improvement. Six (20%) of the 30 patients undergoing PNS placement returned to part-time or full-time work after being unemployed prestimulator implantation. Initial involvement of more than one major peripheral nerve correlated with a poor or no relief rating (p<0.01). Operative modifications that minimize technical complications are described. This study indicates that PNS can provide good relief for RSD that is limited to the distribution of one major nerve.

Electric Stimulation Therapy↗
PubMed2004

[Sonography of peripheral nerves--first part: upper limb].

At sonography, peripheral nerves have a fibrillar appearance, that is tape-like on longitudinal scans and ovoid on transverse scans. Nerves are composed by hypoechoic fascicules within a hyperechoic environment. Less subject to anisotropy and soft to the pressure of the probe, nerves lie between muscles, often with vessels, or within channels. Recent advances in sonographic technology allow accurate imaging of peripheral nerves of the upper and lower limbs, but adequate anatomical and clinical knowledge, as well as rigorous technique are mandatory. The purpose of this general review is to present, as clearly as possible, in two parts, the sonographic features of normal and pathological nerves of upper and lower limbs. This first part will discuss nerves of the upper limb.

Arm↗
PubMed1994

Identification of Gal(beta 1-3)GalNAc bearing glycoproteins at the nodes of Ranvier in peripheral nerve.

A subset of human anti-GM1 ganglioside antibodies cross-reacts with Gal(beta 1-3)GalNAc bearing glycoproteins in peripheral nerve and spinal cord. The same oligosaccharide determinant is recognized by the lectin peanut agglutinin (PNA) which binds at the nodes of Ranvier in intact peripheral nerve. The Gal(beta 1-3)GalNAc bearing glycoproteins were isolated using PNA lectin affinity chromatography followed by separation on Western blot, and the proteins were subjected to partial amino acid sequence analysis. Two major PNA binding glycoproteins were identified in peripheral nerve and spinal cord; one had an approximate molecular weight of 120 kD and had sequence homology to the oligodendrocyte-myelin glycoprotein (OMgp). The other migrated between 70 and 80 kD and had sequence homology to the hyaluronate binding domain of versican, which has been reported to share sequence homology with the 70 kD proteins hyaluronectin and the glial hyaluronic acid binding protein (GHAP). By immunocytochemistry, OMgp was localized to the paranodal region of myelin, and the protein homologous to the hyaluronate binding domain of versican was localized to the nodal gap in peripheral nerve. These PNA binding glycoproteins might be target antigens for autoantibodies in peripheral nerve.

Amino Acid Sequence↗
PubMed2005

[Experimental study of excitation of peripheral nerves in transverse electric field stimulation].

The classical cable function has been used to represent the response of peripheral nerves stimulated by external parallel electric field. Experiments show that peripheral nerves can be activated by perpendicular electric field induced by magnetic pulses, indicating that the activation mechanism needs to be thoroughly investigated. Several excitation properties of peripheral nerves in transverse-field were explored in the present paper. With a human's median nerve in vivo, stimulation threshold, excitation position and the relation between excitation threshold and fiber's radius were studied. The relation between stimulation threshold and stimulation duration was researched with sciatic nerves from toad in vitro. The experimental results verify that the modified cable function is much efficient than the classical cable function. The research will improve the nerve magnetic stimulating technique and be beneficial to further application.

Animals↗
PubMedDate not supplied

Effect of alcohol intake on some disturbances induced by chronic exposure to carbon disulphide in rats. II. Biochemical and ultrastructural alterations in the peripheral nerves.

The effect of chronic ethanol (EtOH) administration on CS2-induced peripheral neuropathy in rats was studied. Rats were exposed to 0.8 mg/l CS2 for 12-15 months and to 10% EtOH as only drink during the last 4 months of the experiment. Some biochemical correlates of Wallerian degeneration of the peripheral nerve were estimated and ultrastructural examinations of the peripheral nerves were performed. It was shown that EtOH augmented the alterations in lipid content provoked by CS2 in the peripheral nerves, i.e. an increase in cholesterol esters and in the ratio of cholesterol esters to free cholesterol (E/F ratio) and a decrease in phospholipid content. The magnitude of ultrastructural changes induced by CS2 in the nerves was increased by EtOH.

Animals↗
PubMed1996

Monoclonal antibody C38 labels surviving retinal ganglion cells after peripheral nerve graft in axotomized rat retina.

C38 is a monoclonal antibody that labels retinal ganglion cells in both intact and axotomized rat retinas. We report here that C38 labeled retinal ganglion cells that survived after optic nerve section and peripheral nerve graft in rats. Furthermore, with combination of the retrograde labeling, we succeeded to distinguish surviving retinal ganglion cells without axonal regeneration from those with regenerating axon.

Animals↗
PubMed1988

Expression of nerve growth factor receptor during human peripheral nerve development.

The expression of NGF receptors on human Schwann cells during development and myelination and in culture was analyzed using a murine monoclonal antibody to human NGF receptor. Nonmyelinated femoral nerves from 13- to 14-week fetuses stained strongly for NGF receptor, whereas tissues from later stages of development showed a decrease in the staining intensity. These changes correlated with the initiation of myelination (17-19 weeks), as observed by phase-contrast and electron microscopy, and the reactivity with monoclonal antibody 4C5, a marker of mature Schwann cells. In adult nerves, only the perineurium and few endoneurial cells were stained with anti-NGF receptor antibody. Cultured human fetal Schwann cells were positive for NGF receptor by immunofluorescence irregardless of donor age or length of time in culture. The decreased staining of NGF receptor with nerve maturation may reflect a dependence of antigen expression on Schwann cell differentiation and/or neuron-Schwann cell interaction.

Cells, Cultured↗
PubMed1994

The use of acellular autologous skeletal muscle grafts in peripheral nerve repair: a morphometrical-morphological study.

Alternative materials for autologous nerve grafts in peripheral nerve surgery have long been investigated. This report describes the use of acellular (freeze-thawed) autologous skeletal muscle grafts (ASMG) to bridge a 2 cm gap in the sciatic nerve of rats. Neurophysiologic and morphometric studies performed 6 weeks after surgical procedure showed for the nine treated Sprague-Dawley rats (Group A) a good axon regeneration rate, although this was lower than that for the control group (Group B), a lower Nerve Conduction Velocity (NCV) and a thinner myelin sheath than in group B (n = 9 Sprague-Dawley rats). In the latter case, complete resection of 2 cm of the sciatic nerve was followed by an immediate coaptation of the proximal and distal ends.

Animals↗
PubMed2001

Differential regulation of P2X(3) mRNA expression by peripheral nerve injury in intact and injured neurons in the rat sensory ganglia.

The P2X(3) receptor is a ligand-gated cation channel activated by the binding of extracellular adenosine 5'-triphosphate (ATP), an agent that has been suggested to have a role in the nociceptive pathway after tissue and nerve injury. After peripheral nerve injury, both down regulation and up regulation of the P2X(3) receptor in sensory ganglion neurons have been observed. The purpose of this study was to examine the precise regulation of P2X(3) mRNA expression in primary sensory neurons after nerve injury. We used two nerve injury models in the rat, the transection of the tibial and common peroneal nerves and the transection of the infraorbital nerve, and observed dorsal root ganglion (DRG) and trigeminal ganglion neurons, respectively. P2X(3) mRNA in both neuron populations was detected by in situ hybridization with an oligonucleotide probe that was confirmed by Northern blot analysis. To identify axotomized neurons, we examined the expression of activating transcription factor 3 (ATF3), which is regarded as a neuronal-injury marker, using immunohistochemistry. In the DRG, the mean percentage of P2X(3) mRNA-labeled neurons relative to the total number of neurons increased from 32.7% in the naive rats to 42.7% at 3 days after injury. The mean percentage of P2X(3) mRNA-labeled neurons in ATF3 immunoreactive (ir) neurons was 29.5% at 3 postoperative days, which gradually decreased to 11.2% at 28 days after injury. In the trigeminal ganglion, the mean percentage of P2X(3) mRNA-labeled neurons was 36.9% at 3 days after injury, versus 26.0% in the naive rats. In the ATF3-ir neurons, the mean percentage of P2X(3) mRNA-labeled neurons was 25.3% at 1 postoperative day and was reduced to 6.1% at 28 postoperative days. The finding that P2X(3) mRNA in ATF3-ir neurons decreased significantly after injury indicates that axotomized neurons decreased the expression of P2X(3) mRNA, despite the increase in P2X(3) mRNA relative to the total number of sensory ganglion neurons. These data strongly suggest that P2X(3) mRNA expression increases in intact neurons and that P2X(3) mRNA in intact neurons may play a role in the pathomechanism of post-nerve injury in primary sensory neurons.

Activating Transcription Factor 3↗
PubMed1986

Stimulation of peripheral nerve regeneration by an isolated nerve segment.

An experimental model in rats was used to assess the stimulant effect of an isolated nerve segment on peripheral nerve regeneration. In a first group of animals, 14 mm of the femoral nerve was removed unilaterally and the gap was bridged with femoral vein taken from the other side. In a second group, the intervention differed in that a 2-mm nerve segment was introduced at the center of the bridging vein. Histological examination was done three months after the operation. In the first group, a newly formed nerve structure was found in the proximal part of the vein, with incipient myelination of nerve fibers. The frequency of nerve fibers decreased with the distance from the proximal nerve stump, with no fibers present in the distal part of the vein. In the second group, a well-developed nerve structure was noted in both the proximal and the distal parts of the bridging vein, with myelination well advanced. Possible reasons for the positive effect of an isolated nerve segment in bridging nerve gaps are discussed.

Animals↗
PubMed1992

The peripheral nerve allograft in the primate immunosuppressed with Cyclosporin A: I. Histologic and electrophysiologic assessment.

Nerve regeneration across peripheral nerve allografts and control autografts in primates immunosuppressed with Cyclosporin A was quantitatively evaluated by electrophysiologic and histologic methods. Twelve cynomolgus monkeys received 3-cm autografts and allografts in contralateral ulnar nerves. They were immunosuppressed with Cyclosporin A at 25 mg/kg per day or placebo vehicle. Morphometric analysis of nerve graft and distal nerve segments was assessed at 1 year after engraftment. Quantitative electrophysiologic studies were performed percutaneously at 6 and 12 months, and compound action potentials were measured directly across the nerve grafts at 1 year. Excellent regeneration was seen across autografts and allografts in Cyclosporin A-treated and placebo-treated recipients.

Action Potentials↗