Normative nerve conductions in the tail of rhesus macaques (Macaca mulatta)

BACKGROUND: The aim of this study was to test the feasibility of using the tail of Macaca mulatta for neurophysiological testing of the peripheral nervous system. METHODS: Motor and sensory nerve conduction studies (NCS) of the tail were obtained by surface stimulation and recording. The technique utilized was novel. Unlike other NCS obtained from other peripheral nerves, this technique did not require any special neurophysiological expertise. RESULTS: The latency of the motor and sensory response was 2.5 +/- 0.71 and 1.1 +/- 0.27 ms respectively. The amplitude of the motor and sensory response was 8.1 +/- 5.1 mV and 14.6 +/- 9.4 microV respectively. Similar to human beings, there was a statistically significant relationship between age and motor amplitude, motor latency and sensory latency. CONCLUSIONS: Based on our results, a relatively simple, reproducible neurophysiological monitoring technique of the peripheral nervous system is possible.     

Postnatal change in lipid composition and nerve conduction of peripheral nerves of young rhesus monkeys.

Body weight, motor and sensory nerve conduction velocities of fore and hind limbs, and lipid composition were measured sequentially in peripheral nerves of 15 rhesus monkeys. Initially measurements were made with monkeys six to eight months of age. There were significant increases in body weight, motor, and sensory nerve conduction and myelin marker lipids over a five months period, but no change was observed in free fatty acids, triglycerides, and esterified cholesterol. These results indicate that myelination continues at least for 11 to 13 months of postnatal age in rhesus monkeys.     

草甘膦胁迫对中华大蟾蜍（Bufo gargarizans）神经冲动产生和传导的影响

应用电生理方法研究了除草剂草甘膦对中华大蟾蜍（Bufo gargarizans Cantor）坐骨神经干冲动产生和传导的影响。用不同浓度的草甘膦溶液对中华大蟾蜍进行胁迫处理,草甘膦有效成分经由皮肤进入蟾蜍体内而作用于神经系统,利用生物信号采集处理系统测定草甘膦胁迫下中华大蟾蜍离体坐骨神经干的应激反应时间、动作电位幅度和冲动传导速度,结果表明：随着草甘膦溶液浓度的升高,中华大蟾蜍坐骨神经干接受刺激后产生冲动所需的时间逐渐延长,动作电位峰值降低,神经冲动传导速度亦逐渐减慢。草甘膦施用后,中华大蟾蜍7d内的平均应激反应时间与草甘膦浓度呈正相关,而动作电位幅度及传导速度均与草甘膦浓度呈负相关。草甘膦溶液浓度达到推荐农田使用浓度1.64~2.87ml/L时,各处理组蟾蜍的应激反应时间、动作电位幅度和冲动传导速度均与对照组差异极显著（P〈0.01）。同时,随着试验处理时间的延长,中华大蟾蜍神经干对刺激的反应变得更为迟钝,神经冲动的传导速度也进一步减慢。回归分析可知,中华大蟾蜍坐骨神经干的应激反应时间与草甘膦施用后天数呈正相关,而神经传导速度与药后天数呈负相关。由此可以说明,草甘膦胁迫条件下,中华大蟾蜍神经细胞对刺激反应的灵敏性降低,动作电位的产生及传导受到一定程度的抑制和阻碍。     

补阳还五汤口服和药浴对损伤的大鼠坐骨神经传导速度的影响

目的探讨补阳还五汤口服加药浴对坐骨神经传导速度的影响。方法60只SD大鼠暴露左侧坐骨神经。对照组只钳夹;实验组钳夹并加用补阳还五汤口服及药浴治疗。观察钳夹前和钳夹切除后大鼠坐骨神经传导速度（SNCV）。结果于2、4、6周分别测对照组、实验组的坐骨神经传导速度（SNCV）。各时间段实验组坐骨神经传导速度恢复快于对照组,P〈0．01。结论补阳还五汤口服加药浴对坐骨神经传导速度有明显的促进作用。     

牛蛙神经冲动产生和传导的低温效应

在5℃和15℃温度条件下,用牛蛙(Rana catesbeiana)离体坐骨神经标本测定0、24、48、96、120、144、168、192、216 h 9个时段的动作电位波幅和传导速度.结果表明:两个温度下离体坐骨神经的动作电位幅度在0 h和24 h差异均不显著,0 h时相对高温(15℃)下动作电位传导速度大于相对低温(5℃),24 h时两个温度下动作电位的传导速度差异不显著,相对高温下48 h时坐骨神经的兴奋性为零.相对低温条件下,坐骨神经兴奋性能维持7 d时间.     

Fenestration in the myelin sheath of nerve fibers of the shrimp: A novel node of excitation for saltatory conduction

Giant nerve fibers of the shrimp family Penaeidae conduct impulses at the velocity highest among all animal species (∼210 m/s; highest in mammals = 120 m/s). We examined these giant and other small nerve fibers morphologically using a differential interference contrast microscope as well as an electron microscope, and found a very specialized form of excitable membrane that functions as a node for saltatory conduction of the impulse. This node appeared under the light microscope as a characteristic pattern of concentrically aligned rings in a very small spot of the myelin sheath. The diameter of the innermost ring of the node was about 5 μm, and the distance between these nodes was as long as 12 mm. Via an electron microscope, these nodes were characterized by a complete lack of the myelin sheath, forming a fenestration that has a tight junction with an axonal membrane. Voltage clamp measurements by a sucrose gap technique demonstrated that the axonal membrane at these fenestration nodes is exclusively excitable and that the large submyelinic space is a unique conductive pathway for loop currents for saltatory conduction through such fenestration nodes. © 1996 John Wiley & Sons, Inc.     

Antibodies to L-periaxin in sera of patients with peripheral neuropathy produce experimental sensory nerve conduction deficits

L-Periaxin is a PDZ-domain protein localized to the plasma membrane of myelinating Schwann cells and plays a key role in the stabilization of mature myelin in peripheral nerves. Mutations in L-periaxin have recently been described in some patients with demyelinating peripheral neuropathy, suggesting that disruption of L-periaxin function may result in nerve injury. In this study, we report the presence of autoantibodies to L-periaxin in sera from two of 12 patients with diabetes mellitus (type 2)-associated neuropathy and three of 17 patients with IgG monoclonal gammopathy of undetermined significance (MGUS) neuropathy, an autoimmune peripheral nerve disorder. By comparison, anti-L-periaxin antibodies were not present in sera from nine patients with IgM MGUS neuropathy or in sera from 10 healthy control subjects. The effect of anti-L-periaxin serum antibody on peripheral nerve function was tested in vivo by intraneural injection. Sera containing anti-L-periaxin antibody, but not sera from age-matched control subjects, injected into the endoneurium of rat sciatic nerve significantly (p < 0.005, n = 3) attenuated sensory-evoked compound muscle action potential (CMAP) amplitudes in the absence of temporal dispersion. In contrast, motor-evoked CMAP amplitudes and latencies were not affected by intraneural injection of sera containing anti-L-periaxin antibody. Light and electron microscopy of anti-L-periaxin serum-injected nerves showed morphologic evidence of demyelination and axon enlargement. Depleting sera of anti-L-periaxin antibodies neutralized the serum-mediated effects on nerve function and nerve morphology. Together, these data support anti-L-periaxin antibody as the pathologic agent in these serum samples. We suggest that anti-L-periaxin antibodies, when present in sera of patients with IgG MGUS- or diabetes-associated peripheral neuropathy, may elicit sensory nerve conduction deficits.     

Pulsed magnetic fields enhance the rate of recovery of damaged nerve excitability

Pulsed magnetic fields (PMFs) have well‐known beneficial effects on nerve regeneration. However, little research has examined the nerve conduction characteristics of regenerating peripheral nerves under PMF. The main goal of this study was to examine the conduction characteristics of regenerating peripheral nerves under PMFs. The sucrose‐gap recording technique was used to examine the conduction properties of injured sciatic nerves of rats exposed to PMF. Following the injury, peripheral nerves were very sensitive to repetitive stimulation. When the stimulation frequency was increased, the amplitude of the compound action potential (CAP) decreased more at 15 days post‐crush injury (dpc) than at 38 dpc. PMF treatment for 38 days after injury caused significant differences in the conduction of CAPs. Moreover, application of PMF ameliorated the abnormal electrophysiological activities of nerves such as hyperpolarizing afterpotentials and delayed depolarizations that were revealed by 4‐aminopyridine (4‐AP). Consequently, characteristic findings in impulse conduction of recovered nerves under PMF indicate that the observed abnormalities in signaling or aberrant ion channel functions following injury may be restored by PMF application. Bioelectromagnetics 32:200–208, 2011. © 2010 Wiley‐Liss, Inc.     

IGF‐I deficient mice show reduced peripheral nerve conduction velocities and decreased axonal diameters and respond to exogenous IGF‐I treatment

Although insulin‐like growth factor‐I (IGF‐I) can act as a neurotrophic factor for peripheral neurons in vitro and in vivo following injury, the role IGF‐I plays during normal development and functioning of the peripheral nervous system is unclear. Here, we report that transgenic mice with reduced levels (two genotypes: heterozygous Igf1^+/− or homozygous insertional mutant Igf1^m/m) or totally lacking IGF‐I (homozygous Igf1^−/−) show a decrease in motor and sensory nerve conduction velocities in vivo. In addition, A‐fiber responses in isolated peroneal nerves from Igf1^+/− and Igf1^−/− mice are impaired. The nerve function impairment is most profound in Igf1^−/− mice. Histopathology of the peroneal nerves in Igf1^−/− mice demonstrates a shift to smaller axonal diameters but maintains the same total number of myelinated fibers as Igf1^+/+ mice. Comparisons of myelin thickness with axonal diameter indicate that there is no significant reduction in peripheral nerve myelination in IGF‐I–deficient mice. In addition, in Igf1^m/m mice with very low serum levels of IGF‐I, replacement therapy with exogenous recombinant hIGF‐I restores both motor and sensory nerve conduction velocities. These findings demonstrate not only that IGF‐I serves an important role in the growth and development of the peripheral nervous system, but also that systemic IGF‐I treatment can enhance nerve function in IGF‐I–deficient adult mice. © 1999 John Wiley & Sons, Inc. J Neurobiol 39: 142–152, 1999     

Extrapolation of an empirical elbow muscle co-activation relationship to a novel task set: implications for predictions of individual muscle demands

Biomechanical optimisation models applying efficiency-based objective functions often underestimate antagonist contributions. Previous work has quantified an empirical co-activation relationship in the elbow musculature, demonstrating that implementing this relationship as a constraint in an elbow muscle force prediction model improves muscle force predictions. The current study evaluated this modified model by extrapolating the co-activation relationship to 36 novel isometric unilateral, right-handed exertions, including those requiring greater intensity of effort and performed in different postures. Surface electromyography was recorded from the elbow flexors and extensors. Novel extrapolative co-activation relationships were developed and used as constraints in a muscle force prediction model. Model predictions using both constraints were compared with empirical biophysical data. Predictions by the modified model were more consistent with biophysical data than those by the original model for the novel exertions. Novel co-activation relationships did not further enhance predictions when compared with the previous relationship, suggesting that extrapolation of the previous relationship is feasible.     

Development of an image-based technique to examine joint congruency at the elbow

Identifying joint contact in articular joints is important for both the biomechanical investigation of joint mechanics and the study of osteoarthritis. The purpose of this study is to develop a proximity mapping technique to non-invasively determine joint congruency, as a surrogate of joint contact. To illustrate the capabilities of this algorithm, a cadaveric upper extremity was positioned at varying degrees of elbow flexion. This technique was validated using a gold standard experimental casting technique. The pattern of the cast showed an excellent agreement with the generated proximity map using the inter-bone distance algorithm. The results from this study agree with the results of previous studies examining joint contact at the elbow both in the location and in the tracking of the joint contact throughout elbow flexion. Ultimately, this technique will lead to an increased understanding of the effect of malalignment and instability of the joint on contact mechanics.     

Two novel non-destructive biomarkers to assess PAH-induced oxidative stress and porphyrinogenic effects in crabs

Two novel, non-destructive assays were developed to evaluate contaminant-induced lipid peroxidation (thiobarbituric acid-reacting substances, TBARS, levels) and haem biosynthesis disruption (porphyrin excretion) in decapod crabs. A laboratory experiment was conducted whereby pie-crust crabs (Cancer novaezelandiae) were fed cockles (Austrovenus stutchburyi) collected from a contaminated and reference site and TBARS levels and porphyrin excretion determined using fluorometric analysis in urine samples. Pyrene metabolite levels were also measured in the same urine samples to assess polycyclic aromatic hydrocarbon (PAH) exposure. Contaminant-exposed crabs exhibited elevated urinary TBARS and porphyrin levels and a strong correlation was found between these two assays and the urinary pyrene metabolite concentrations. However, there was large within-treatment variability, which precluded a clear separation between the control and the impacted group. Nevertheless, consistency in the direction of the response shows that the biomarkers reflect pollutant levels and validates the use of these simple techniques from human medicine for environmental assessments.     

Hydrogen peroxide permeation across liposomal membranes: a novel method to assess structural flaws in liposomes

Hydrogen peroxide permeation across large multilamellar vesicles of defined and complex lipid composition was shown to obey precise kinetic relationships for the activity of the occluded catalase. Careful assay conditions precluded simultaneous peroxidative damage to the lipids. The kinetic data was consistent with a barrier role for the bilayer for hydrogen peroxide permeation. More interestingly, hydrogen peroxide permeation across liposomes of complex lipid mixtures exhibited osmotic inhibition of permeation of hydrogen peroxide. On the other hand, purified egg lecithin vesicles did not exhibit any effect of external osmolality on hydrogen peroxide permeation in an experimentally defined non-lytic zone of external osmolarity. These results argue in favour of a heterogeneous, heteroporous structure of bilayers with complex lipid composition.     

Effect of vitamin C and E supplementation in modulating the peripheral nerve conduction following cold exposure in humans

Exposure to an extremely cold environment without proper protection leading to hypothermia is an emergency, one of the several complications of which is impairment in nerve conduction. Our previous work in the rat model has shown the beneficial effect of vitamin C in modulating the effect of hypothermia on nerve conduction. The present study aimed to evaluate the effect of vitamins C and E, administered alone or in combination, in modulating the effect of mild hypothermia on human ulnar nerve conduction. The study was carried out on 26 volunteers divided into three groups: group I received vitamin C supplementation (2000 mg/day in a single dose and 1,000 mg/day for the next 6 days), group II received vitamins C and E in combination (1,000 mg and 800 mg respectively in a single dose and 500 mg and 400 mg respectively for the next 6 days) and group III received vitamin E (800 mg in a single dose and the same for the next 6 days). The recordings were carried out before and after single and weekly supplementation in each group. There was a fall in ulnar nerve conduction velocity with a reduction in the oral temperature of 2–2.5 °C. Vitamin C administered alone and in combination with vitamin E reduced the fall in ulnar nerve conduction velocity. Prior supplementation with vitamin C and E could help ameliorate the impairment in human ulnar nerve conduction due to hypothermia.     

Control scheme of two d.o.f. CPM device to suppress the extension of ligament of the elbow

Continuous passive motion (CPM) is an orthopedic treatment or a physiotherapy and has been applied after surgery. After surgery for the injured ulna collateral ligament (UCL) which is a major clinical case in the elbow joint, the reaction force at the hand of the patient increases and may be excessively large due to an increase of the joint stiffness. For this, it will be effective to reduce the excessive reaction force by controlling pro-/supination of forearm. The UCL in the elbow joint is extended due to pro-/supination of forearm, but the excessive extension may aggravate the injury of the UCL. Thus, it is required to suppress both the excessive extension of the UCL and the reaction force. In this paper, a control scheme of CPM device that can suppress both the excessive extension of the UCL and the reaction force is proposed, and its effectiveness is confirmed from the experimental results.     

Neurotrophin-3-induced production of nerve growth factor is suppressed in Schwann cells exposed to high glucose: involvement of the polyol pathway

Development of hypesthesia, a loss of sensitivity to stimulation, is associated with impaired regeneration of peripheral sensory fibers, in which Schwann cells play a key role by secreting nerve growth factor (NGF). Recent clinical trials indicated that an inhibitor of aldose reductase (AR), the rate-limiting enzyme in the polyol pathway, significantly improved hypesthesia in diabetic patients. The fact that AR is localized in Schwann cells led us to investigate the role of the polyol pathway in NGF production of isolated Schwann cells. Among various endogenous factors examined, increased production of NGF was demonstrated in the cells treated with neurotrophin-3 (NT-3) for 24 h. NT-3-induced NGF production was significantly suppressed when cells were cultured in the medium containing high glucose. In these cells, the levels of glutathione (GSH) and cAMP-response element binding protein (CREB) were reduced, whereas the level of activated nuclear factor-kappaB (NF-kappaB) was elevated. These changes were abolished when an AR inhibitor fidarestat was included in the medium. NT-3-induced NGF production was further attenuated in the cells treated with an inhibitor of GSH synthesis. Together, the enhanced polyol pathway activity under high-glucose conditions seems to elicit reduced NT-3-induced NGF production in Schwann cells. Enhanced oxidative stress linked to the polyol pathway activity may mediate this process.     

A review of methods to assess coactivation in the spine

Coactivation is an important component for understanding the physiological cost of muscular and spinal loads and their associations with spinal pathology and potentially myofascial pain. However, due to the complex and dynamic nature of most activities of daily living, it can be difficult to capture a quantifiable measure of coactivation. Many methods exist to assess coactivation, but most are limited to two-muscle systems, isometric/complex analyses, or dynamic/uniplanar analyses. Hence, a void exists in that coactivation has not been documented or assessed as a multiple-muscle system under realistic complex dynamic loading. Overall, no coactivation index has been capable of assessing coactivation during complex dynamic exertions. The aim of this review is to provide an understanding of the factors that may influence coactivation, document the metrics used to assess coactivity, assess the feasibility of those metrics, and define the necessary variables for a coactivation index that can be used for a variety of tasks. It may also be clinically and practically relevant in the understanding of rehabilitation effectiveness, efficiency during task performance, human-task interactions, and possibly the etiology for a multitude of musculoskeletal conditions.     

Axon regeneration across the site of injury in the optic nerve of the newt Triturus pyrrhogaster

Summary The process by which axons regenerate following a freeze injury to the optic nerve of the newt was analyzed by light and electron microscopy. Freezing destroys cellular constituents in a one millimeter segment of the nerve, leaving intact the basal lamina and the blood supply to the eye. No axons are seen at the site of injury one to seven days post lesion. This contrasts with the persistence of normal-appearing but severed unmyelinated axons within the cranial stump which thus give a false appearance of early regeneration. The first axon sprouts traverse the lesion and enter the cranial stump by ten days. The number of regenerating axons increases rapidly thereafter with no signs of random growth at the site of injury. These axon sprouts tend to be somewhat larger than normal unmyelinated axons and contain dense core vesicles and abnormal organelles similar to those in growing axons in tissue culture. The persisting basal lamina inside the optic sheath appears to provide continuity across the site of injury, to orient axon sprouts, and to favor an orderly process of axon regeneration without neuroma formation.The authors wish to express their gratitude to Barbara Heindel and Jill Jones for extremely helpful technical assistance. This work was supported by grants NS 10864 and NS 05666 from the U.S. Public Health Service and by the Medical Research Service of the Veterans Administration     

Bisphenol A inhibits compound action potentials in the frog sciatic nerve in a manner independent of estrogen receptors

Although the endocrine disruptor bisphenol A (BPA) is reported to inhibit nerve conduction, the underlying mechanisms are unclear. Therefore, in the present study, we examined the effect of BPA on compound action potentials (CAPs) recorded from the frog sciatic nerve using the air-gap method. Treatment of the sciatic nerve with BPA (0.5 mM) for 20 min reduced the peak amplitude of the CAP by approximately 60% in a partially reversible manner. The reduction in the CAP peak amplitude was concentration-dependent, with a half-maximal inhibitory concentration (IC₅₀) value of 0.31 mM. This effect of BPA was unaffected by an estrogen-receptor antagonist, 4-hydroxytamoxifen, which by itself reduced CAP peak amplitude, with an IC₅₀ value of 0.26 mM (comparable to that of BPA). The natural estrogen 17β-estradiol, at the highest dissolvable concentration (0.05 mM), had an effect similar to that of BPA. The IC₅₀ value of BPA was comparable to those of some local anesthetics in inhibiting frog CAPs. Our findings suggest that BPA inhibits nerve conduction in a manner independent of estrogen receptors. This action of BPA may underlie, at least in part, the neurotoxicity of the compound.