Laser beam coupling into nerve fiber myelin allows one to assess its structural membrane properties

Kutuzov, Nikolay; Brazhe, Alexey; Lyaskovskiy, Vladimir L.; Максимов, Г. В.

doi:10.1117/1.jbo.20.5.050501

Cited by 4 publications

(5 citation statements)

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“…Due to their high lipid and protein content, myelin sheaths have a high refractive index ( n = 1.455) compared to neural cell somata ( n = 1.358) and the aqueous extracellular medium ( n ≅ 1.335) [ 14 , 21 ]. Myelinated axons have been shown to trap and guide laser light through internal reflection [ 22 ], but they also constitute high-refractive-index tubular microstructures and thus fulfil the requirements for anisotropic scattering as described for dentine [ 15 ].…”

Section: Resultsmentioning

confidence: 99%

Optic-nerve-transmitted eyeshine, a new type of light emission from fish eyes

et al. 2017

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BackgroundMost animal eyes feature an opaque pigmented eyecup to assure that light can enter from one direction only. We challenge this dogma by describing a previously unknown form of eyeshine resulting from light that enters the eye through the top of the head and optic nerve, eventually emanating through the pupil as a narrow beam: the Optic-Nerve-Transmitted (ONT) eyeshine. We characterize ONT eyeshine in the triplefin blenny Tripterygion delaisi (Tripterygiidae) in comparison to three other teleost species, using behavioural and anatomical observations, spectrophotometry, histology, and magnetic resonance imaging. The study’s aim is to identify the factors that determine ONT eyeshine occurrence and intensity, and whether these are specifically adapted for that purpose.ResultsONT eyeshine intensity benefits from locally reduced head pigmentation, a thin skull, the gap between eyes and forebrain, the potential light-guiding properties of the optic nerve, and, most importantly, a short distance between the head surface and the optic nerves.ConclusionsThe generality of these factors and the lack of specifically adapted features implies that ONT eyeshine is widespread among small fish species. Nevertheless, its intensity varies considerably, depending on the specific combination and varying expression of common anatomical features. We discuss whether ONT eyeshine might affect visual performance, and speculate about possible functions such as predator detection, camouflage, and intraspecific communication.Electronic supplementary materialThe online version of this article (doi:10.1186/s12983-017-0198-9) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Optic-nerve-transmitted eyeshine, a new type of light emission from fish eyes

et al. 2017

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“…Here, the maximum position of the Gaussian band around 1524 cm −1 was calculated from the Gaussian fitting procedure depth‐dependently and used for the determination of the molecular structure of carotenoids in the lipid phase in the entire SC. Kutuzov et al44,45 indicated that the I 1524 / I 1160 intensity ratio correlates with the trans / gauche ‐conformation in the order of lipids that contain carotenoids in the myelin nerve membrane. Direct translation of this method to the SC is not applicable, as the peak at 1160 cm −1 originates not only from carotenoids but also from keratin 63,64.…”

Section: Methodsmentioning

confidence: 99%

“…[33,37] In the second pathway (outside to inside), the carotenoids are secreted via eccrine sweat glands or sebaceous glands to the skin surface [38,39] and penetrate from the surface into the SC, saturating the superficial SC layers. [40] The same process is also known for lipophilic vitamin E. [41,42] As carotenoids are lipophilic substances, they are incorporated in lipid bilayers [43] and could potentially influence the organization and fluidity of lipid membranes [44][45][46] and their physical properties. [43,46] In this, in vivo study the interaction between the carotenoids and the molecular structure of ICL in the SC was investigated depthdependently by using confocal Raman microscopy (CRM).…”

Section: Introductionmentioning

confidence: 99%

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The non‐homogenous distribution and aggregation of carotenoids in the stratum corneum correlates with the organization of intercellular lipids in vivo

Choe

Ri²,

Schleusener

et al. 2019

Experimental Dermatology

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The human stratum corneum (SC) contains an abundant amount of carotenoid antioxidants, quenching free radicals and thereby protecting the skin. For the precise measurements of the depth-dependent carotenoid concentration, confocal Raman microscopy is a suitable method. The quantitative concentration can be determined by the carotenoid-related peak intensity of a Gaussian function approached at ≈1524 cm −1 using non-linear regression. Results show that the carotenoid concentration is higher at the superficial layers of the SC then decreases to a minimum at 20% SC depth and increases again towards the bottom of the SC. In the present work, two carotenoid penetration pathways into the SC are postulated. The first pathway is from the stratum granulosum to the bottom of the SC, while in the second pathway, the carotenoids are delivered to the skin surface by sweat and/or sebum secretion and penetrate from outside. The carotenoids are aggregated at the superficial layers, which are shown by high correlation between the aggregation states of carotenoids and the lateral organization of lipids. At the 30%-40% SC depths, the ordered and dense lipid molecules intensify the lipid-carotenoid interactions and weaken the carotenoid-carotenoid interaction and thus exhibit the disaggregation of carotenoids. At 90%-100% SC depths, the carotenoid-lipid interaction is weakened and the carotenoids have a tendency to be aggregated. Thus, the molecular structural correlation of carotenoid and SC lipid might be reserved in the intercellular space of the SC and also serves as the skeleton of the intercellular lipids.

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“…Carotenoids in myelin can possibly mediate the potential-induced myelin reorganization, as well as regulate the interaction of external signaling molecules with the membrane. It was shown that both lipid and carotenoid molecules are sensitive to the extracellular ATP and acetylcholine, and thus are possible mediators of the myelin membrane restructuring [ 13 – 15 ]. The aim of current investigation was to study the conformation of myelin phospholipid fatty acids and carotenoid during demyelination.…”

Section: Introductionmentioning

confidence: 99%

Study of myelin structure changes during the nerve fibers demyelination

2017

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Raman, NMR and EPR spectroscopy and electrophysiology methods were used to investigate the excitability and the packaging of myelin lipid layers and its viscosity during nerve exposure to pronase E. It was established that during exposure of nerve to pronase E the action potential (AP) conduction velocity and the Schwann cell (SC) (or myelin) water ordering increases, but the nerve myelin refractive index and internode incisions numbers decrease. This effect included two periods–short- and long-time period, probably, because the first one depends on SC protein changes and the second one–on the nerve fiber internode demyelination. It was concluded that high electrical resistance of myelin, which is important for a series of AP conduction velocity, not only depends on nerve fiber diameter and the myelin lipid composition, but also on the regularity of myelin lipid fatty acids and myelin lipid layer packing during the axoglial interaction.

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Laser beam coupling into nerve fiber myelin allows one to assess its structural membrane properties

Cited by 4 publications

References 13 publications

Optic-nerve-transmitted eyeshine, a new type of light emission from fish eyes

Optic-nerve-transmitted eyeshine, a new type of light emission from fish eyes

The non‐homogenous distribution and aggregation of carotenoids in the stratum corneum correlates with the organization of intercellular lipids in vivo

Study of myelin structure changes during the nerve fibers demyelination

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