Miller fisher syndrome – A rare complication of covid-19 infection

The COVID-19 virus can present with various neurological signs and symptoms involving both the central and peripheral nervous systems. Miller Fisher syndrome (M.F.S.), a variant of Landry Guillain Barre Syndrome (L.G.B.S.), presents with ataxia, areflexia, and ophthalmoplegia. It can develop during and after COVID-19 illness. We are reporting a case of the Miller Fisher variant of L.G.B.S. following a COVID-19 infection. We found no difference in clinical presentation, electrophysiological studies, severity, recovery, and treatment in our patient compared to a non-covid related M.F.S. Our goal is to add a case of the COVID-19-associated Miller Fisher variant of L.G.B.S. to already existing limited literature through this case report.

The PACAP/PAC1 Receptor System and Feeding

Pituitary adenylyl cyclase activating polypeptide (PACAP) belongs to the vasoactive intestinal polypeptide (VIP)/secretin/glucagon superfamily. PACAP is present in two forms (PACAP-38 and PACAP-27) and binds to three guanine-regulatory (G) protein-coupled receptors (PAC1, VPAC1, and VPAC2). PACAP is expressed in the central and peripheral nervous systems, with high PACAP levels found in the hypothalamus, a brain region involved in feeding and energy homeostasis. PAC1 receptors are high-affinity and PACAP-selective receptors, while VPAC1 and VPAC2 receptors show a comparable affinity to PACAP and VIP. PACAP and its receptors are expressed in the central and peripheral nervous systems with moderate to high expression in the hypothalamus, amygdala, and other limbic structures. Consistent with their expression, PACAP is involved in several physiological responses and pathological states. A growing body of literature suggests that PACAP regulates food intake in laboratory animals. However, there is no comprehensive review of the literature on this topic. Thus, the purpose of this article is to review the literature regarding the role of PACAP and its receptors in food intake regulation and to synthesize how PACAP exerts its anorexic effects in different brain regions. To achieve this goal, we searched PubMed and reviewed 68 articles regarding the regulatory action of PACAP on food intake. Here, we present the literature regarding the effect of exogenous PACAP on feeding and the role of endogenous PACAP in this process. We also provide evidence regarding the effect of PACAP on the homeostatic and hedonic aspects of food intake, the neuroanatomical sites where PACAP exerts its regulatory action, which PACAP receptors may be involved, and the role of various signaling pathways and neurotransmitters in hypophagic effects of PACAP.

The PACAP/PAC1 Receptor System and Feeding

Pituitary adenylyl cyclase activating polypeptide (PACAP) belongs to the vasoactive intestinal polypeptide (VIP)/secretin/glucagon superfamily. PACAP is present in two forms, PACAP-38 and PACAP-27, and binds to three guanine-regulatory (G) protein-coupled receptors (PAC1, VPAC1, and VPAC2). PACAP is expressed in the central and peripheral nervous systems with high PACAP levels found in the hypothalamus, a brain region involved in feeding and energy homeostasis. PAC1 receptors are high-affinity and PACAP-selective receptors, while VPAC1 and VPAC2 receptors show a comparable affinity to PACAP and VIP. PACAP and its receptors are expressed in the central and peripheral nervous systems, with moderate to high expression in the hypothalamus, amygdala, and other limbic structures. Consistent with their expression, PACAP is involved in several physiological responses and pathological states. A growing body of literature suggests that PACAP regulates food intake in laboratory animals. However, there is no comprehensive review of the literature on this topic. Thus, the purpose of this article is to review the literature regarding the role of PACAP and its receptors in food intake regulation and to synthesize how PACAP exerts its anorexic effects in different brain regions. To achieve this goal, we searched PubMed and reviewed 68 articles regarding the regulatory action of PACAP on food intake. Here, we present the literature regarding the effect of exogenous PACAP on feeding and the role of endogenous PACAP in this process. We also provide evidence regarding the effect of PACAP on the homeostatic and hedonic aspects of food intake, the neuroanatomical sites where PACAP exerts its regulatory action, which PACAP receptors may be involved, and the role of various signaling pathways and neurotransmitters in hypophagic effects of PACAP.

Features of diseases of the musculoskeletal and peripheral nervous systems in workers of metallurgical production in modern conditions

Manufacturing industries, including metallurgy, are the backbone of the country’s economy. A number of technological operations involve the impact of physical overload, heating microclimate, static load, and often entails the development of diseases of the musculoskeletal and peripheral nervous systems. The clinical picture of such patients is dominated by pain in various parts of the spinal column, in some cases, combined localization. The analysis of the results of the examination of the connection of diseases of the musculoskeletal and peripheral nervous systems with the profession, carried out by employees of a large metallurgical enterprise of the Republic of Bashkortostan (RB), using the archival material of the FBUN clinic «Ufa Research Institute of Occupational Medicine and Human Ecology» was carried out. The group of the main professions of the enterprise includes: wire drawing machine, wire rewinder, caliper, pyrometrist, laboratory assistant for physical and mechanical tests, automatic machine for cold landing machines, mechanic-repairman, sorter-delivery of metal. During the analyzed period, in 117 cases, the workers of the enterprise confirmed the professional etiology of the disease. The nosological structure in 60 % of cases of the first established occupational diseases is represented by diseases of the musculoskeletal system and connective tissue. A significant part of diseases of occupational etiology was detected in persons aged 50 to 59 years. Workers of the studied professional groups are at the highest risk of developing diseases of the musculoskeletal and peripheral nervous systems of professional etiology, which is due to the specific conditions of their professional activity. Establishing a connection between the disease and the profession is characterized by late detection, at the stage of pronounced clinical symptoms with the formation of persistent disability.

Biophysics of Nervous Embryo-Fetal Development

The dynamical processes of living systems are characterized by the cooperative interaction of many units. This claim enables us to portray the embryo-fetal development of the central and peripheral nervous systems in terms of assemblies of building blocks. We describe how the structure and arrangement of nervous fibers is - at least partially - dictated by biophysical and topological constraints. The far-flung field of soft-matter polymers/nematic colloids sheds new light on the neurulation in mammalian embryos, suggesting an intriguing testable hypothesis: the development of the central and peripheral nervous systems might be correlated with the occurrence of local thermal changes in embryo-fetal tissues. Further, we show a correlation between the fullerene-like arrangement of the cortical microcolumns and the Frank-Kasper phases of artificial quasicrystals assemblies. The last, but not the least, we explain how and why the multisynaptic ascending nervous fibers connecting the peripheral receptors to the neocortical areas can be viewed as the real counterpart of mathematical tools such as knot theory and braid groups. Their group structure and generator operations point towards a novel approach to long-standing questions concerning human sensation and perception, leading to the suggestion that the very arrangement and intermingling of the peripheral nervous fibers contributes to the cortical brain activity. In touch with the old claims of D’Arcy Thompson, we conclude that the arrangement and the pattern make the function in a variety of biological instances, leading to countless testable hypotheses.