Dynamic early clusters of nodal proteins contribute to node of Ranvier assembly during myelination of peripheral neurons

Voltage-gated sodium channels cluster in macromolecular complexes at nodes of Ranvier to promote rapid nerve impulse conduction in vertebrate nerves. Node assembly in peripheral nerves is thought to be initiated at heminodes at the extremities of myelinating Schwann cells and fusion of heminodes results in the establishment of nodes. Here we show that assembly of 'early clusters' of nodal proteins in the murine axonal membrane precedes heminode formation. The Neurofascin (Nfasc) proteins are essential for node assembly, and the formation of early clusters also requires neuronal Nfasc. Early clusters are mobile and their proteins are dynamically recruited by lateral diffusion. They can undergo fusion not only with each other but also with heminodes thus contributing to the development of nodes in peripheral axons. The formation of early clusters constitutes the earliest stage in peripheral node assembly and expands the repertoire of strategies that have evolved to establish these essential structures.

Carboxytherapy in the practice of an occupational pathologist: experience of use in cervical dorsopathy in workers of harmful professions

The task of ensuring the working capacity of the country’s industrial potential is to preserve the health of employees of enterprises with harmful working conditions. High rates of general morbidity and disability of the working population due to vertebrogenic diseases of the spine, the genesis of which is associated with organ overstrain, microtraumatization and vibration exposure, make the problem of treatment, prevention and rehabilitation of this pathology a priority in occupational medicine. In the present study, the expediency of using carboxytherapy in the treatment of cervical dorsopathies in 2 groups of patients working in harmful professions has been studied, in one of which, along with basic drug treatment, physiotherapy exercises and massage, injections of purified carbon dioxide into paravertebral points are included in the complex of therapy. At the end of the course of treatment in the group of patients receiving carboxytherapy, a more significant improvement in clinical and electrophysiological parameters was achieved: a decrease in the intensity of pain syndrome according to a visual analogue scale by 73.3 %, myofascial syndrome by 33.3 %, expansion of the range of motion by 40 %; according to stimulation electroneuromyography and rheovasography — improvement of nerve impulse conduction along the peripheral nerves of the upper extremities and the roots of the C6–8 — Th1 spinal nerves by 35 %, the hemodynamics of peripheral blood vessels of the upper extremities by 45 %. The extensive physiological properties of carbon dioxide, the availability and safety of the method, the absence of negative consequences, the effectiveness shown in the study allows us to recommend the use of carboxytherapy in occupational pathological practice in the treatment of vertebrogenic reflex syndromes in workers in hazardous occupations.

PKC–NF-κB are involved in CCL2-induced Nav1.8 expression and channel function in dorsal root ganglion neurons

Cytokine CCL2 is responsible for promoting voltage-gated sodium Nav1.8 current density and expression, which mediates nerve impulse conduction and induces inflammatory nociception. PKC phosphorylates Nav1.8 to increase its current density and PKC–NF-κB are involved in inducing the up-regulation of Nav1.8.

Glycogen replenishment following exercise: effects of denervation and tenotomy

To examine the role of the nervous system in the rapid replenishment of muscle glycogen that occurs after exhaustive exercise, glycogen stores and glycogen synthetase activity of normal gastrocnemius muscles of untrained and trained guinea pigs were compared to glycogen and synthetase activity of trained gastrocnemius muscles that were denervated or tenotomized immediately after exhaustive exercise and then allowed to recover for 48 h. The trained tenotomized muscles, but not the denervated muscles, had significantly (P smaller than 0.05) less glycogen than the trained normal muscles. These results suggest that neither nerve impulse conduction nor tropic substances contained in neural tissue proximal to the site of denervation mediate glycogen replenishment after exercise. The active, glucose 6-phosphate independent (I) form of glycogen synthetase activity was reduced by both denervation and tenotomy at 48 h after exercise with no significant (P greater than 0.05) differences detected for the total of I and D (glucose 6-phosphate dependent) synthetase activity. Synthetase I relative to total synthetase activity was similar in trained and untrained normal muscles, both of which had significantly (P smaller than 0.05) greater relative I activities than denervated or tenotomized muscles. These synthetase data show that elevated glycogen stores following recovery from exercise may be observed in the absence of increased levels of glycogen synthetase activity.