Individual mechanisms underlying peripheral nerve damage when exposed to metallic mercury

2020 ◽  
Vol 60 (12) ◽  
pp. 918-924
Author(s):  
Dina V. Rusanova ◽  
Oleg L. Lakhman ◽  
Galina M. Bodienkova ◽  
Irina V. Kudaeva ◽  
Natalya G. Kuptsova
Keyword(s):  
Peripheral Nerve ◽  
Peripheral Nerves ◽  
Blood Circulation ◽  
The State ◽  
Contact Period ◽  
Peripheral Nerve Damage ◽  
Demyelinating Disorders ◽  
Peripheral Blood Circulation ◽  
Antibodies To Dna

Introduction. There is a lack of knowledge of the pathophysiological mechanisms that form peripheral nerve disorders in mercury lesions of professional origin. The study aims to reveal the mechanisms underlying peripheral nerve damage in the long-term post-contact period of chronic mercury intoxication (CMI). Materials and methods. Fifty-one people had the diagnosis of a long-term period of CMI. The post-contact period was 8.5±2.6 years. The authors compared the results with a control group of 26 healthy men who had no contact with toxic substances. Stimulating electroneuromyography was performed. We studied the body systems that could contribute to the formation of disorders in the peripheral nerves. Changes in peripheral hemodynamics were studied using reovasography. The content of autoantibodies, neuron-specific enolase, serotonin, histamine, catecholamines (epinephrine, dopamine), metanephrine, and neurotrophin-3 was reviewed. The content of ceruloplasmin, secondary products of lipid peroxidation processes, reduced glutathione, the activity of superoxide dismutase and the content of nitric oxide levels were determined. Results. The study established pathogenetic structural links of peripheral nerve disorders. The autoimmune process's role was to increase the range of antibodies to the MAG protein and increase the level of antibodies to DNA. Violations of elastic-tonic properties of peripheral vessels could be associated with the functional state of motor axons. The increased content of neurotransmitters is related to the state of peripheral blood circulation; the most pronounced changes were on the legs, which could contribute to the occurrence and maintenance of vasoconstriction. The role of oxidative stress in the formation of demyelinating disorders in patients' peripheral nerves in the long-term period of CRI is possible. Conclusion. Neuroimmunological processes has an essential role in the development of peripheral nerve demyelination was shown, which consists in an increase in the content of antibodies to the MAG protein expressed on Schwann cells of peripheral nerves and in an increase in the level of antibodies to DNA involved in the formation of demyelinating changes when exposed to metallic mercury. The revealed pathological changes in the state of the peripheral blood circulation, characterized by a violation of the vessels' elastic-tonic properties, leading to demyelination of motor axons in patients in the long-term period of CMI. The increased content of neurotransmitters in the examined is of great importance in the state of peripheral circulation. Pronounced changes in blood circulation are established on the lower extremities, which may be associated with the predominance of α-adrenergic receptors in the arterial bed and may contribute to the occurrence and maintenance of vasoconstriction in the legs. The relationship between changes in indicators of oxidative stress, consisting of a decrease in the value of superoxide dismutase and reduced glutathione, and the formation of demyelinating disorders of peripheral nerves in patients in the long-term period of CMI has been proved.

scholarly journals Revascularization of the lower limb in multisegmental atherosclerotic lesions.

2019 ◽  
Vol 21 (3) ◽  
pp. 59-60
Author(s):  
O V Pinchuk ◽  
A V Obraztsov ◽  
V V Yamenskov ◽  
A A Rakov ◽  
A A Abrosimov
Keyword(s):  
Surgical Treatment ◽  
Positive Result ◽  
Lower Limb ◽  
Blood Circulation ◽  
The State ◽  
Individual Approach ◽  
Atherosclerotic Lesions ◽  
Vascular Bed ◽  
Direct Compensation

The issues of surgical treatment of multisegmental atherosclerotic lesions of lower limb arteries are considered. Data and analysis of own observations are given. The experience of 9 rare shunt operations of «long» shunts is summarized. Such operations, as an alternative to amputation, can be performed with an adequate assessment of the state of the arterial vascular bed and a strictly individual approach. In some cases, such methods of revascularization provide direct compensation for the blood circulation of the limb with a long-term positive result.

scholarly journals Electronic Module for Photoplethysmography аnd Pulse Oximetry

2018 ◽  
pp. 15-21
Author(s):  
Igor Isupov ◽  
Rimma Zatrudina
Keyword(s):  
Blood Flow ◽  
Pulse Oximetry ◽  
Peripheral Blood ◽  
Blood Circulation ◽  
Open Architecture ◽  
Study Region ◽  
Interference Tests ◽  
Pulse Oximeters ◽  
Peripheral Blood Circulation

Methods of pulse oximetry and photoplethysmography are widely used in clinical medicine and practice of biomedical research outside the clinic. The advantages of the method are high efficiency of preparation for the diagnostic procedure, non-invasive, complete safety for health. The method provides the possibility of unlimited long - term monitoring of the dynamics of saturation and desaturation of hemoglobin. In combination with the above, subject to the qualitative registration of photoplethysmograms, the method allows the calculation and analysis of a number of indicators of peripheral blood circulation: the total pulse blood flow to the study region, the tone of arterial vessels of different diameters, the state of capillary blood flow. Most modern foreign models of pulse oximeters are integrated devices that provide measurement of a very limited set of physiological parameters: the percentage of hemoglobin oxygen saturation and pulse rate. The range of pulse oximeters containing the interface with the personal computer and providing operational calculation of indicators of peripheral photoplethysmograms is small. Such devices have a fairlyhigh cost and are not portable. The development of domestic integrated electronic devices is extremely relevant, allowing along with obtaining information about blood oxygenation to perform continuous monitoring of peripheral blood circulation. The authors developed an electronic module that provides long-term registration of photoplethysmograms in the infrared and red areas of the light spectrum. The electronic module is made exclusively with the use of domestic active radio elements – discrete semiconductor devices and integrated circuits. The device was developed in full compliance with the import substitution policy pursued by the President and the Government of the Russian Federation. The advantage of the device is the "open architecture" of the electronic circuit, which provides four analog signals suitable for further digitization. The signals contain information about pulsating and non-pulsating components of the optical density of biological tissue in the infrared and red ranges of the spectrum. The device has an electronic filter of mains interference. Tests of the device demonstrated high quality of photoplethysmograms. This makes it possible tosuccessfullyuse the device for studies of hemoglobin oxygenation and peripheral hemodynamics.

scholarly journals Theoretical and practical considerations regarding the study of cranial circulation by measuring blood pressure at the two ends of the carotid artery

2020 ◽  
Vol VI (2) ◽  
pp. 95-119
Author(s):  
F. N. Telyatnik
Keyword(s):  
Blood Pressure ◽  
Carotid Artery ◽  
Peripheral Nerve ◽  
Lower Limb ◽  
Blood Circulation ◽  
The State ◽  
The Body ◽  
The Other ◽  
Small Arteries ◽  
The One

Of all the methods of studying cranial blood circulation, which I will not list here, the best is the one in which the state of cranial blood circulation is judged by the blood pressure in the two ends of the carotid artery. Hrthle was the first to observe this method, and therefore the method itself is often called the Hrthle method. However, as Hrthle himself says, the idea of ​​a method existed before. So, A. Dastre and J. Morat, for the purpose of proving the existence of vasomotor fibers for the lower limb in n. ischiadicus, determined the blood pressure in the central end of one a. cruralis and in the peripheral end the other; on the side last n. ischiadicus overcame. With irritation of a peripheral nerve cut, the pressure increased in the peripheral end of the а. cruralis, remaining unchanged in the central cut. This increase in pressure in the operated limb, which coincides with the unchanged pressure in the rest of the body, proves that (with the indicated irritation) there is a reduction in small arteries.

scholarly journals Glial TGFβ activity promotes axon survival in peripheral nerves

2021 ◽  
Author(s):  
Alex Lassetter ◽  
Megan Corty ◽  
Romina Barria ◽  
Amy Sheehan ◽  
Sue Aicher ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Peripheral Nerves ◽  
Wallerian Degeneration ◽  
Tgfβ Signaling ◽  
Age Dependent ◽  
Support Mechanisms ◽  
Axon Survival ◽  
Tgfβ Superfamily

Axons can represent the majority of the volume of a neuron and are energetically very demanding. Specialized glia ensheathe axons and are believed to support axon function and maintenance throughout life, but molecular details of glia-neuron support mechanisms remain poorly defined. Here we identify a collection of secreted and transmembrane genes that are required in glia for long-term axon survival in vivo. We show that key components of the TGFβ superfamily are required cell-autonomously in glia for peripheral nerve maintenance, although their loss does not disrupt glial morphology. We observe age-dependent neurodegeneration in the absence of glial TGFβ signaling that can be rescued by genetic blockade of Wallerian degeneration. Our data argue that glial TGFβ signaling normally acts to promote axon survival and suppress neurodegeneration.

scholarly journals Substantiation of the use of indices of the heart rate variability in predicting the development of polyneuropathies in workers of coal enterprises

2020 ◽  
Vol 99 (7) ◽  
pp. 688-692
Author(s):  
Margarita O. Gidayatova ◽  
Ilya D. Martynov ◽  
Anastasia V. Yamshchikova ◽  
Arnold N. Fleishman
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Peripheral Nerve ◽  
Coal Mining ◽  
High Frequency ◽  
Peripheral Nerves ◽  
Impulse Conduction ◽  
Peripheral Nerve Damage ◽  
High Frequency Oscillations ◽  
Coal Enterprises

Introduction. One of the most common forms of occupational diseases of the peripheral nervous system is autonomic-sensory polyneuropathy. For Kuzbass, which is one of the leaders in coal mining, the problem of early diagnosis and prevention of polyneuropathies is the most urgent.The purpose of this study was to determine autonomic disorders and their role in the development of occupational polyneuropathy in workers of coal enterprises in Kuzbass.Material and methods. 72 male miners aged from 40 to 64 years with working experience from 15 to 36 years were examined. The control group consisted of 18 subjects of the same age, engaged in light physical or mental work that had no occupational risk factors. To assess the degree of peripheral nerve damage electroneuromyography was performed in all cases; indices of spectral and nonlinear heart rate variability were used to determine the state of autonomic regulation.Results. No signs of polyneuropathy were detected in 20 subjects of the examined workers of coal enterprises according to electroneuromyography data. The miners with diagnosed polyneuropathy were divided into 3 groups according to the severity of the lesion of the impulse conduction along the peripheral nerves. In the miners with no signs of polyneuropathy, who exposed to harmful production factors, a statistically significant decrease in the power of high-frequency oscillations of the heart rate variability spectrum was determined. The subjects with initial disorders of the impulse conduction showed a progressive decrease in high-frequency oscillations, with moderate signs of polyneuropathy, there were a sympathetic predominance and increased influence of suprasegmental autonomic centers. In the development of severe disorders of the impulse conduction along the peripheral nerves, depression of oscillations in all frequency ranges and rigidity of the heart rate are characteristic.Conclusion. The obtained data confirm the influence of autonomic dysfunction on the development of occupational polyneuropathy. The analysis of heart rate variability is an important tool for evaluating autonomic regulation and can be used in mass medical examinations. A decrease in spectral and nonlinear parameters in coal-mining workers is an early sign of the disorder of autonomic regulation, which allows predicting the occurrence and development of peripheral nerve damage.

scholarly journals MODERN ASPECTS OF THE USE OF NERVE CONDUCTORS IN PERIPHERAL NERVOUS SYSTEM INJURY

2020 ◽  
Vol 8 (2) ◽  
pp. 137-144
Author(s):  
O. O. Potapov ◽  
O. P. Kmyta ◽  
O. O. Tsyndrenko
Keyword(s):  
Peripheral Nerve ◽  
Polylactic Acid ◽  
Peripheral Nerves ◽  
Nerve Repair ◽  
Polyglycolic Acid ◽  
Peripheral Nerve Injuries ◽  
Nerve Injuries ◽  
Peripheral Nerve Damage ◽  
Nerve Recovery ◽  
Good Biocompatibility

Peripheral nerve injuries account for 4 % of all injuries, and the consequences of trauma are a major medical and social problem, since they are characterized by a significant and long-term decline in limb function, and a high level of disability in patients. According to our data, up to 40% of patients sought specialized care for more than 6 months after the injury, and 19.9% were treated conservatively for an unreasonably long period of time. It led to an increase in the portion of unsatisfactory treatment results, since the prognosis of the further functional and useful degree of nerve recovery worsens with increasing time after injury. The main objective was to select the optimal option of biocompatible material for implementation in practice in case of traumatic peripheral nerve damage. Materials and methods. The analysis of medical literature for 2015–2020 was conducted. First of all, it should be noted that modern non-biological resorbable tubes are made of polyglycolic and polylactic acids. Non-resorbable tubes, including silicone, have shown undesirable effects, including axon compression during regeneration and the reaction of a fibrous foreign body. Hollow cylindrical tubes can be manufactured in several ways, such as electrospinning, crosslinking, physical film rolling, injection molding, melt extrusion, and braiding. Adequate surgical treatment of peripheral nerve injuries requires that the surgeon, in addition to an accurate knowledge of the anatomical details of the affected area, would also be familiar with microsurgical methods and had necessary equipment to operate. The main procedure in peripheral nerve surgery is the restoration of nerve continuity, which can be obtained by direct coaptation between the two ends of a severed nerve or by the introduction of nerve grafts to replace a defect in nerve tissue. Polyester is the most common synthetic material used in neural tissue engineering, along with polylactic acid, polycaprolactone, and polyglycolic acid. In combination with mesenchymal stem cells of the bone marrow, polylactic acid showed better results and accelerated the recovery of peripheral nerves. Polylactic acid directed the migration of Schwann's cells and induced the formation of a normal nervous structure. It was proved that the polycaprolactone material had an effect similar to that of autografts in nerve repair, and its characteristics were better than in a polylactic acid tube. Polyglycolic acid also possesses sufficient mechanical properties and can be used to repair a nerve defect. Artificial synthetic materials have good biocompatibility and biodegradability with minimal toxicity. For the production of high-purity polymer monomers, which are necessary for the manufacture of the frame, much time and financial costs are required. Moreover, the elasticity and hardness of such materials are imperfect. Three main natural biomaterials are used in tissue repair: collagen, silk, and gelatin. Collagen tube is the most widely used biological material in clinical practice. Silk materials with the protein fibroin, which promote the release of certain substrates, such as nerve growth factor particles, and provide more nutrients and a more favorable microenvironment for nerve repair, are worth noticing. Silk fibroin has good compatibility with the neurons of the dorsal root ganglia and supports cell growth. Gelatin materials are preferred due to the reduction of micromanipulation during nerve recovery. Natural biomaterials are easy to obtain in sufficient quantities; they have good biocompatibility and biodegradability and are easily absorbed by the body. However, each natural biomaterial has its drawbacks. Some of them are brittle or break down in a humid environment. Some natural materials are insoluble in water and traditional organic solvents, which limits their use. One of the most widely used biopolymers of natural origin is chitosan. Chitosan, derived by chitin deacetylation, plays a supporting, protective, and guiding role in the early stage of recovery of peripheral nerves and can provide a relatively stable, localized microenvironment during regeneration. Chitosan is absorbed and gradually decomposed in the late phase of recovery and regeneration of the nervous system. Issues regarding graphene-based nanomaterials use are considered. Graphene is a two-dimensional carbon nanomaterial with good optical, electrical and mechanical properties. It should be noted that when graphene nanoparticles incorporate into a chitosan or gelatin frame and are used to repair peripheral nerve damage in rats, this has contributed to the regeneration of the damaged nerve more quickly. Graphene also reduced the inflammatory response and accelerated the migration of endogenous neuroblasts. Hence, the use of these materials is not well understood due to the significant duration of recovery of the denervated proximal end of the nerve, so further research is needed to identify the advantages or disadvantages of their use.

Power Projects and Covid-19: A Practical Analysis of the Relevance of Force Majeure Clauses under the Standardised Power Purchase and Implementation Agreements of Uganda

2020 ◽  
Vol 1 (2) ◽  
pp. 189-193
Author(s):  
Aisha Naiga ◽  
Loyola Rwabose Karobwa
Keyword(s):  
Renewable Energy ◽  
Renewable Energy Sources ◽  
Clean Energy ◽  
The State ◽  
Energy Sources ◽  
Policy Goals ◽  
Force Majeure ◽  
Practical Analysis ◽  
Energy Justice

Over 90% of Uganda's power is generated from renewable sources. Standardised Implementation Agreements and Power Purchase Agreements create a long-term relationship between Generating Companies and the state-owned off-taker guaranteed by Government. The COVID-19 pandemic and measures to curb the spread of the virus have triggered the scrutiny and application of force majeure (FM) clauses in these agreements. This article reviews the FM clauses and considers their relevance. The authors submit that FM clauses are a useful commercial tool for achieving energy justice by ensuring the continuity of the project, despite the dire effects of the pandemic. Proposals are made for practical considerations for a post-COVID-19 future which provides the continued pursuit of policy goals of promoting renewable energy sources and increasing access to clean energy, thus accelerating just energy transitions.

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