scholarly journals Flat Electrode Contacts for Peripheral Nerve Stimulation

2019 ◽  
Author(s):  
Jesse E Bucksot ◽  
Andrew J Wells ◽  
Kimiya C Rahebi ◽  
Vishnoukumaar Sivaji ◽  
Mario Romero-Ortega ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Nerve Stimulation ◽  
In Vivo Experiments ◽  
Cuff Electrode ◽  
Uniform Current ◽  
Sciatic Nerves ◽  
Initial Results ◽  
Rabbit Sciatic Nerve

AbstractThe majority of available systems for nerve stimulation use circumferential stimulation electrodes inside an insulating cuff, which produce largely uniform current density within the nerve. Flat stimulation electrodes that contact only one side of the nerve may provide advantages including simpler implantation, ease of production, and more resistance to mechanical failure. However, it is possible that the flat configuration will yield inefficient fiber recruitment due to a less uniform current distribution within the nerve. Here we tested the hypothesis that flat electrodes will require higher current amplitude to achieve effective stimulation than circumferential designs. Computational modeling and in vivo experiments were performed to evaluate fiber recruitment in different nerves and different species using a variety of electrode designs. Initial results demonstrated similar fiber recruitment in the rat vagus and sciatic nerves with a standard circumferential cuff electrode and a cuff electrode modified to approximate a flat configuration. Follow up experiments comparing true flat electrodes to circumferential electrodes on the rabbit sciatic nerve confirmed that fiber recruitment was equivalent between the two designs. These findings demonstrate that flat electrodes represent a viable design for nerve stimulation that may provide advantages over the current circumferential designs for applications in which the goal is uniform activation of the nerve.

scholarly journals An investigation of arterial insufficiency in the rat hindlimb Correlation of skeletal muscle bloodflow and glucose utilization in vivo

1986 ◽  
Vol 240 (2) ◽  
pp. 395-401 ◽  
Author(s):  
R A Challiss ◽  
D J Hayes ◽  
G K Radda
Keyword(s):  
Skeletal Muscle ◽  
Sciatic Nerve ◽  
Glucose Uptake ◽  
Nerve Stimulation ◽  
Linear Correlation ◽  
Glucose Utilization ◽  
Fold Increase ◽  
Artery Ligation ◽  
Sciatic Nerve Stimulation

Muscle bloodflow and the rate of glucose uptake and phosphorylation were measured in vivo in rats 7 days after unilateral femoral artery ligation and section. Bloodflow was determined by using radiolabelled microspheres. At rest, bloodflow to the gastrocnemius, plantaris and soleus muscles of the ligated limb was similar to their respective mean contralateral control values; however, bilateral sciatic nerve stimulation at 1 Hz caused a less pronounced hyperaemic response in the muscles of the ligated limb, being 59, 63 and 49% of their mean control values in the gastrocnemius, plantaris and soleus muscles respectively. The rate of glucose utilization was determined by using the 2-deoxy[3H]glucose method [Ferré, Leturque, Burnol, Penicaud & Girard (1985) Biochem. J. 228, 103-110]. At rest, the rate of glucose uptake and phosphorylation was statistically significantly increased in the gastrocnemius and soleus muscles of the ligated limb, being 126 and 140% of the mean control values respectively. Bilateral sciatic nerve stimulation at 1 Hz caused a 3-5-fold increase in the rate of glucose utilization by the ligated and contralateral control limbs; furthermore, the rate of glucose utilization was significantly increased in the muscles of the ligated limb, being 140, 129 and 207% of their mean control values respectively. For the range of bloodflow to normally perfused skeletal muscle at rest or during isometric contraction determined in the present study, a linear correlation between the rate of glucose utilization and bloodflow can be demonstrated. Applying similar methods of regression analysis to glucose utilization and bloodflow to muscles of the ligated limb reveals a similar linear correlation. However, the rate of glucose utilization at a given bloodflow is increased in muscles of the ligated limb, indicating an adaptation of skeletal muscle to hypoperfusion.

scholarly journals In vivo Photonic Stimulation of Sciatic Nerve with a 1470 nm Laser

2016 ◽  
Vol 26 (3) ◽  
Author(s):  
Marie Dautrebande ◽  
Pascal Doguet ◽  
Simon-Pierre Gorza ◽  
Jean Delbeke ◽  
Yohan Botquin ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Sciatic Nerve ◽  
Nerve Stimulation ◽  
Muscle Activation ◽  
Radiant Exposure ◽  
Stimulation Of

Photonic stimulation is a new modality of nerve stimulation, which could overcome some of the electrical stimulation limitations. In this paper, we present the results of photonic stimulation of rodent sciatic nerve with a 1470 nm laser. Muscle activation was observed with radiant exposure of 0.084 J/cm<sup>2</sup>.

Arsenic-induced toxicity: effect on protein composition in sciatic nerve

2006 ◽  
Vol 25 (11) ◽  
pp. 667-674 ◽  
Author(s):  
A Vahidnia ◽  
F Romijn ◽  
M Tiller ◽  
G B van der Voet ◽  
F A de Wolff
Keyword(s):  
Sciatic Nerve ◽  
Peripheral Nerves ◽  
Protein Composition ◽  
Arsenic Compounds ◽  
Neurotoxic Effects ◽  
Electrophysiological Studies ◽  
Male Wistar Rats ◽  
Sciatic Nerves ◽  
L Proteins

Exposure to arsenic compounds may lead to skin and lung cancer and various disorders such as vascular disease and peripheral neuropathy in humans. Peripheral arsenic neurotoxicity has been demonstrated clinically and in electrophysiological studies. Patients intoxicated with arsenic show neurological symptoms in their feet and hands. These patients show significantly lower nerve conduction velocities (NCVs) in their peripheral nerves in comparison with controls. The mechanism of arsenic peripheral nervous system (PNS) toxicity, however, has never been described before. This is the first study to investigate the toxicity of arsenic on the PNS. Male Wistar rats were exposed to arsenite given as a single dose i.v. After sacrifice, sciatic nerves were excised and the protein composition was analysed. Protein analysis of sciatic nerves showed disappearance of neurofilament and fibroblast proteins in rats treated with arsenite doses of 15 and 20 mg/kg in comparison with the control groups. Some fibroblast protein bands had disappeared in the 20-mg/kg dose group. The analysed neurofilament-M and-L proteins decreased dose dependency over time. arsenic affects the composition of proteins in the rat sciatic nerve, especially the neurofilaments. The reduction of signals in Western blot analysis reveals changes in cytoskeletal composition, which may well lead to neurotoxic effects in vivo.

scholarly journals Hypoxia-induced up-regulation of miR-27a promotes paclitaxel resistance in ovarian cancer

2020 ◽  
Vol 40 (4) ◽  
Author(s):  
Lanlan Feng ◽  
Fangrong Shen ◽  
Jinhua Zhou ◽  
Yan Li ◽  
Rong Jiang ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Regulatory Mechanism ◽  
Chemotherapy Resistance ◽  
Paclitaxel Resistance ◽  
In Vivo Experiments ◽  
Hypoxic Environment ◽  
Skov3 Cells

Abstract Ovarian cancer (OC) is a malignant tumor with high mortality in women. Although cancer patients initially respond to paclitaxel chemotherapy following surgery, most patients will relapse after 12–24 months and gradually die from chemotherapy resistance. In OC, cancer cells become resistant to paclitaxel chemotherapy under hypoxic environment. The miR-27a has been identified as an oncogenic molecular in ovarian cancer, prostate cancer, liver cancer etc. In addition, the miR-27a is involved in hypoxia-induced chemoresistance in various cancers. However, the role of miR-27a in hypoxia-induced OC resistance remains unclear. The aim of the present study was to investigate the regulatory mechanism of miR-27a in hypoxia-induced OC resistance. The expression of HIF-1α induced Hypoxia overtly up-regulated. At the same time, hypoxia increased viability of Skov3 cells and decreased cell apoptosis when treated with paclitaxel. The expression of the miR-27a was obviously up-regulated under hypoxia and involved in hypoxia-induced paclitaxel resistance. Follow-up experiments portray that miR-27a improved paclitaxel resistance by restraining the expression of APAF1 in OC. Finally, we further elucidated the important regulatory role of the miR-27a-APAF1 axis in OC through in vivo experiments. According to our knowledge, we first reported the regulation of miR-27a in hypoxia-induced chemoresistance in OC, providing a possible target for chemoresistance treatment of OC.

scholarly journals Injury-Induced HSP27 Expression in Peripheral Nervous Tissue Is Not Associated with Any Alteration in Axonal Outgrowth after Immediate or Delayed Nerve Repair

2021 ◽  
Vol 22 (16) ◽  
pp. 8624
Author(s):  
Lena Stenberg ◽  
Derya Burcu Hazer Rosberg ◽  
Sho Kohyama ◽  
Seigo Suganuma ◽  
Lars B. Dahlin
Keyword(s):  
Sciatic Nerve ◽  
Nerve Repair ◽  
Positive Influence ◽  
Diabetic Rats ◽  
Axonal Outgrowth ◽  
Short Delay ◽  
Hsp27 Expression ◽  
Sciatic Nerves ◽  
Repair Models

We investigated injury-induced heat shock protein 27 (HSP27) expression and its association to axonal outgrowth after injury and different nerve repair models in healthy Wistar and diabetic Goto-Kakizaki rats. By immunohistochemistry, expression of HSP27 in sciatic nerves and DRG and axonal outgrowth (neurofilaments) in sciatic nerves were analyzed after no, immediate, and delayed (7-day delay) nerve repairs (7- or 14-day follow-up). An increased HSP27 expression in nerves and in DRG at the uninjured side was associated with diabetes. HSP27 expression in nerves and in DRG increased substantially after the nerve injuries, being higher at the site where axons and Schwann cells interacted. Regression analysis indicated a positive influence of immediate nerve repair compared to an unrepaired injury, but a shortly delayed nerve repair had no impact on axonal outgrowth. Diabetes was associated with a decreased axonal outgrowth. The increased expression of HSP27 in sciatic nerve and DRG did not influence axonal outgrowth. Injured sciatic nerves should appropriately be repaired in healthy and diabetic rats, but a short delay does not influence axonal outgrowth. HSP27 expression in sciatic nerve or DRG, despite an increase after nerve injury with or without a repair, is not associated with any alteration in axonal outgrowth.

Biocompatibility of Hylan Polymers in Various Tissue Compartments

1995 ◽  
Vol 394 ◽  
Author(s):  
N.E. Larsen ◽  
E. Leshchiner ◽  
E.A. Balazs ◽  
C. Belmonte
Keyword(s):  
Adverse Effect ◽  
Sciatic Nerve ◽  
Peripheral Nerve ◽  
Tissue Reaction ◽  
Tissue Response ◽  
Medical Applications ◽  
Biological Compatibility ◽  
Sciatic Nerves ◽  
Tissue Compartments

AbstractHylans (hyaluronan derivatives) retain the biological compatibility of the natural hyaluronan and have enhanced rheological properties which expands their utility in medical applications. Hylan materials (hylan A fluid, hylan B gel) were evaluated in a variety of tissue compartments for local and systemic tissue reaction (gross and microscopic), residence time and overall behavior in vivo. Hylan material was implanted into the subcutaneous, intradermal, submucosal, intramuscular, eye (vitreus, anterior chamber, trabecular meshwork), and neural (sciatic nerve) tissues at volumes ranging from 0.50 ml/kg to 20 ml/kg (2.5 mg/kg to 100 mg/kg). There was no difference in tissue response to hylan implants at the various ‘doses’ evaluated; all samples tested were observed to be biocompatible and did not elicit significant tissue response. Therefore, tissue reaction of hylan implants was not dependent on dose or concentration of hylan administered, since implantation of small amounts resulted in the same response as implantation of large amounts of material. In one of the most sensitive tests of biocompatibility, hylan was found to have no adverse effect on nerve regeneration (severed sciatic nerves in rat), and the results indicated that hylan materials “regeneration-friendly” environment for peripheral nerve growth as commatpearriaelds tpor othveid BedS Sa controls.Hylan materials provide biologically and physically compatible intercellular matrices which are useful in a variety of medical applications, including use as viscosurgical and viscoprotective tools (to maintain space, separate and protect tissues) and as viscosupplementation devices and implants.

High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species

2007 ◽  
Vol 293 (3) ◽  
pp. H1498-H1507 ◽  
Author(s):  
Noriko Sakai ◽  
Risuke Mizuno ◽  
Nobuyuki Ono ◽  
Hiroyuki Kato ◽  
Toshio Ohhashi
Keyword(s):  
Reactive Oxygen Species ◽  
Sciatic Nerve ◽  
Reactive Oxygen ◽  
High Oxygen ◽  
Dependent Manner ◽  
Oxygen Species ◽  
Low Oxygen ◽  
Rat Sciatic Nerve ◽  
Sciatic Nerves

Microcirculation of the sheath of the rat sciatic nerve fiber was investigated by using an intravital microscope, and changes in the diameter of the epineurial arterioles in response to highly oxygenated Krebs-bicarbonate solution were evaluated. Superfusion of low-oxygen (0%) Krebs-bicarbonate solution (LKS) onto rat sciatic nerves did not affect changes in the diameter of the arterioles. Nifedipine, a Ca2+-channel blocker, caused a dose-dependent dilation of the epineurial arterioles in LKS. In contrast, superfusion of high-oxygen (21%) Krebs-bicarbonate solution (HKS) onto rat sciatic nerves significantly constricted the epineurial arterioles in a time-dependent manner. The HKS-induced constriction of the epineurial arterioles was significantly reduced by treatment with 120 U/ml superoxide dismutase (SOD) alone or 5,000 U/ml catalase alone. In the presence of 120 U/ml SOD plus 5,000 U/ml catalase, 10−4 M tempol, 10−6 M diphenyleneiodium, 2 × 10−4 M apocynin, or 10−6 M allopurinol, the HKS-induced constriction of the epineurial arterioles completely disappeared. These results suggest that superfusion of highly oxygenated solution onto rat sciatic nerves constricts the epineurial arterioles through reactive oxygen species (ROS), including superoxide and hydrogen peroxide, and that production of superoxide involves a NADPH oxidase- or xanthine oxidase-dependent pathway. In conclusion, ROS play significant roles in the regulation of microcirculation of rat sciatic nerves in vivo.

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