Animals ; Macaca mulatta ; Nerve Regeneration ; Peripheral Nerve Injuries ; physiopathology ; Peripheral Nerves ; physiology ; Rats

Assessment of peripheral nerve injury is a common task in forensic practice. As an objective assistance of inspection, electrophysiological examination is significant in the evaluation of peripheral nerve function after injury. There are currently several methods of electrophysiological examination, including I-T curve, EMG, NCV and SEP. Because electrophysiological examination can assess the injury and regeneration of peripheral nerve injury at different times, it is valuable to estimate prognosis of peripheral nerve injury in forensic medicine. Besides the electrophysiological examination, evaluation of the peripheral nerve injury needs to combine other clinical manifestations to provide an accurate appraisal.
Electrodiagnosis/methods* ; Electromyography/methods* ; Forensic Medicine ; Humans ; Neural Conduction/physiology* ; Peripheral Nerve Injuries ; Peripheral Nerves/physiopathology*

The purpose of the present study was to observe whether primary afferent Abeta-fiber is involved in the information transmission between peripheral terminals of adjacent dermatomes. The dorsal cutaneous nerve branches of spinal nerves from T(8) to T(12) segments were cut proximally. One peripheral stump end of the cut nerves was dissected into a few filaments for the examination of mechanoreceptive properties of single Abeta-fibers and their discharges were observed while the other end was stimulated antidromically. Fifty Abeta-units were recorded in forty-two intact rats. After an electrical stimulation (0.45 mA, 0.1 ms, 20 Hz, for 10 s) was delivered to the stimulated nerve, the size of the receptive field of 60.6% (n=33) Abeta-fibers extended. The mean area of receptive fields of all examined units enlarged from 8.94+/-6.51 mm(2) to 20.34+/-16.17 mm(2) (P<0.01) and the shapes of the receptive fields of 81.8% (n=20) units changed from a dot, round or ellipse with its long axis in parallel with the longitudinal axis of the body to an oblique ellipse with the longitudinal axis of the body. The mechanoreceptive threshold of 68.0% (n=50) units decreased with a reduction in mean threshold from 2.37+/-1.24 to 2.29+/-1.24 mN (P<0.05). The duration of these changes in mechano-receptive properties increased from 52.23+/-9.27 to 56.93+/-15.76 min. Meanwhile, increasing discharge was found in 50.0% (n=50) units but lasted only for 1.52+/-0.46 min. The changes in mechanoreceptive properties appeared simultaneously with discharge changes but had longer duration than that of discharge change (P<0.01). Discharges changes usually appeared in those units with the changes in mechanoreceptive properties following an antidromical electrical stimulation of adjacent spinal segment. These results suggest that low-threshold mechanoreceptive Abeta-fibers are affected by antidromical electrical stimulation of the cutaneous nerve from an adjacent spinal segment, indicating that information transmission occurs between the two endings of peripheral afferent nerves from adjacent spinal segments without any involvement of the central nervous system, and that Abeta-fibers are involved in the process of information transmission between peripheral terminals from adjacent spinal segments.
Afferent Pathways ; physiology ; Animals ; Electric Stimulation ; Mechanoreceptors ; physiology ; Neural Conduction ; physiology ; Peripheral Nerves ; physiology ; Rats ; Rats, Sprague-Dawley ; Skin ; innervation ; Spinal Nerves ; physiology

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 ; Bufo bufo ; Electric Stimulation ; Electromagnetic Fields ; Electrophysiology ; Humans ; Magnetics ; Median Nerve ; physiology ; Peripheral Nerves ; physiology ; Sciatic Nerve ; physiology

OBJECTIVETo evaluate the effects of degradation time and permeability of polymeric conduits on nerve regeneration.

METHODSAfter establishment of rat models with over 10 mm gap of sciatic nerve in right hind legs,four kinds of poly (ester, carbonate) nerve conduits was used to bridge the gaps and one group without conduit in gaps was used as control. The nerve regeneration and conduit degradation were examined both macroscopically and microscopically. The contraction of the muscle controlled by regenerated nerve was measured electrophysiologically at 4, 12 and 20 weeks after the operation.

RESULTBiodegradation time of nerve conduits in vivo was as fellows: 12 weeks in group A,4 weeks in group B and group C,and 20 weeks in group D,respectively. The histological quality of regenerative sciatic neurofibra in group A was the best among all groups (Mean rank 53.17, 38.83, 26. 60, 49.17 and 20.23,P<0.005), but the inflammatory reaction in group A was only less than that in group D and more than that in the other groups (Mean rank 45.87, 36.27, 34. 83, 51.63 and 21.4,P=0.001). The responsive rates of tibialis anterior muscle for electric stimulation in group A, B, C and D were 93.33%, 60%,20% and 73. 33%, respectively (P<0.005).

CONCLUSIONAbsorbable conduits with relatively good permeability and appropriate middle degrade time improve nerve regeneration and renovate function.

Action Potentials ; Animals ; Male ; Nerve Regeneration ; Peripheral Nerves ; physiology ; Rats ; Rats, Sprague-Dawley

Mechanisms of acupuncture and moxibustion for treatment of hypertension have been studied extensively from poly-aspects, poly-levels and poly-links. The present paper reviews the studies on nervous regulation, humoral regulation and regulation of peripheral vessel resistance and other pathways and their relationships in recent ten years, and indicates further perfecting these studies from the following aspects: studies on the mechanism of section and combination of blood pressure-decreasing points, relationship of time-effect and dose-effect of acupuncture and moxibustion, and studies on mechanisms of functions of nerve-endocrine-immune system.
Acupuncture Therapy ; Brain ; physiology ; Endothelins ; physiology ; Humans ; Hypertension ; physiopathology ; therapy ; Moxibustion ; Neurotransmitter Agents ; physiology ; Peripheral Nerves ; physiology ; Renin-Angiotensin System ; physiology ; Vascular Resistance

The classical cable function has been used to represent the response of peripheral nerves stimulated by external parallel electric field. It can not describe the excitation of peripheral nerves stimulated by perpendicular electric field. In this paper, responses of the nodes of Ranvier to transverse-field are deeply investigated by mathematic simulation and in-vitro experiments. The paper demonstrates that, under perpendicular electric field stimulation, the responses evoke a two-stage process including an initial polarization and the actual change of the transmembrane potential. It is the net inward current along a radial direction of the node of Ranvier that causes the peripheral nerve excitation. Based on the two-stage process, a novel model is introduced to describe peripheral nerves stimulated by transverse-field, and the classical cable function is modified. The new model and the improved cable function are verified by several in-vitro experiments. They can be used to represent peripheral nerves responses by arbitrary electric field stimulation.
Animals ; Bufo bufo ; Electric Conductivity ; Electric Stimulation ; Electromagnetic Fields ; Electrophysiology ; Membrane Potentials ; Models, Biological ; Nerve Fibers ; physiology ; Peripheral Nerves ; physiology ; Ranvier's Nodes ; physiology ; Sciatic Nerve ; physiology

Peripheral nerve impairment is a common complication in surgery, clinical researchers always do nerve sutrure using microsurgical technique and adjuvant treatment to improve peripheral nerve regeneration. Western medicine used usually adjuvant drugs, such as neurotrophic factors,are limited by their defects in clinical application. Traditional Chinese medicines (TCMs) classifies peripheral nerve impair as flaccidity Zheng and arthromyodynia, and considers that it is the result of stagnant blood block in the meridians and vessels, deficient of Qi and blood and disuse of bones and muscles. So, drugs usually have the function of invigorating vital energy, activating blood circulation and dredging collaterals. Mono-drugs include astragalus, Salvia miltiorrhiza, Astragali Radix, Epimedii Folium and so on. Extracts of TCMs have Ginkgo Folium, Cervi Cornu Pantotrichum, Achyranthis Bidentatae Radix, and so on. To be ready for further study and development, TCMs which can promote the peripheral nerve regeneration were reviewed by the literatures of the latest years.
Animals ; Drugs, Chinese Herbal ; pharmacology ; Humans ; Nerve Growth Factors ; pharmacology ; Nerve Regeneration ; drug effects ; Peripheral Nerves ; drug effects ; physiology

OBJECTIVETo study the combined effect of low temperature and vibration on function of peripheral circulation and nerve.

METHODS64 rabbits were divided into control group, low temperature group, vibration group and combined effect group randomly, 16 each group. The changes of concentration of ET, Ang II, NO in plasma and SCV, amplitude of sensory nerve action potential, latency of sensory nerve action potential, MCV, distal amplitude of motor nerve, and distal latency of motor nerve were measured before and after experiment.

RESULTSAfter experiment, the concentration of ET, Ang II, NO and SCV, amplitude of sensory nerve action potential, latency of sensory nerve action potential, MCV, distal amplitude of motor nerve, and distal latency of motor nerve were (68.84+/-14.81) pg/ml, (544.01+/-70.20) pg/ml, (123.73+/-9.58) nmol/ml, (25.36+/-6.96) m/s, (1.84+/-0.65) microV, (4.05+/-1.04) m/s, (27.40+/-6.05) m/s, (1.60+/-0.52) microV, (3.51+/-1.30) m/s respectively in low temperature group; (70.22+/-15.02) pg/ml, (540.77+/-68.25) pg/ml, (129.46+/-11.99) nmol/ml, (27.69+/-6.16) m/s, (2.19+/-0.53) microV, (3.86+/-0.89) m/s, (30.03+/-5.21) m/s, (1.65+/-0.49) microV, (3.36+/-l.11) m/s respectively in vibration group; (88.47+/-13.20) pg/ml, (687.38+/-101.44) pg/ml, (70.66+/-4.99) nmol/ml, (20.82+/-3.65) m/s, (1.21+/-0.64) microV, (5.05+/-0.94) m/s, (19.97+/-4.37) m/s, (1.09+/-0.49) microV, (4.49+/-1.26) m/s respectively in combined effect group; compared with pre-experiment, the concentration of ET and Ang II in low temperature group, vibration group and combined effect group were increased after experiment, and the NO was decreased (P<0.05); the nerve conduct velocity and amplitude was decreased and the latency was delayed (P<0.05). After experiment, the concentrations of ET and Ang II in combined effect group were higher than low temperature group and vibration group, and the concentration of NO in combined effect group was lower than low temperature group and vibration group (P<0.05). After experiment, the SCV and MCV in combined effect group were slower than low temperature group and vibration group; the amplitude of sensory nerve action potential and distal amplitude of motor nerve were less than low temperature group and vibration group; the latency of sensory nerve action potential and distal latency of motor nerve in combined effect group was longer than low temperature group and vibration group. The factorial analysis results indicated the synergistic effect between low temperature and vibration (P<0.05).

CONCLUSIONVibration-induced peripheral vascular impairment and nerve impairment would be intensified by low temperature.

Animals ; Blood Circulation ; physiology ; Cold Temperature ; adverse effects ; Female ; Male ; Peripheral Nerves ; physiopathology ; Rabbits ; Vibration ; adverse effects

BACKGROUNDPeripheral nerve injury causes a high rate of disability and a huge economic burden, and is currently one of the serious health problems in the world. The use of nerve grafts plays a vital role in repairing nerve defects. Acellular nerve grafts have been widely used in many experimental models as a peripheral nerve substitute. The purpose of this study was to test the biomechanical properties of acellular nerve grafts.

METHODSThirty-four fresh sciatic nerves were obtained from 17 adult male Wistar rats (age of 3 months) and randomly assigned to 3 groups: normal control group, nerve segments underwent no treatment and were put in phosphate buffered saline (pH 7.4) and stored at 4°C until further use; physical method group, nerve segments were frozen at -196°C and then thawed at 37°C; and chemical method group, nerve segments were chemically extracted with the detergents Triton X-200, sulfobetaine-10 (SB-10) and sulfobetaine-16 (SB-16). After the acellularization process was completed, the structural changes of in the sciatic nerves in each group were observed by hematoxylin-eosin staining and field emission scanning electron microscopy, then biomechanical properties were tested using a mechanical apparatus (Endura TEC ELF 3200, Bose, Boston, USA).

RESULTSHematoxylin-eosin staining and field emission scanning electron microscopy demonstrated that the effects of acellularization, demyelination, and integrity of nerve fiber tube of the chemical method were better than that of the physical method. Biomechanical testing showed that peripheral nerve grafts treated with the chemical method resulted in some decreased biomechanical properties (ultimate load, ultimate stress, ultimate strain, and mechanical work to fracture) compared with normal control nerves, but the differences were not statistically significant (P > 0.05).

CONCLUSIONNerve treated with the chemical method may be more appropriate for use in implantation than nerve treated with the physical method.

Animals ; Biomechanical Phenomena ; Male ; Microscopy, Electron, Scanning ; Peripheral Nerve Injuries ; therapy ; Peripheral Nerves ; physiology ; ultrastructure ; Rats ; Rats, Wistar ; Sciatic Nerve ; physiopathology ; ultrastructure ; Tissue Engineering