Fiber Cross-section Research Articles

Numerical Simulation Analysis of the Seismic Performance of Precast Bridge Piers

Precast technology is increasingly favoured by bridge engineers, and the seismic performance of precast bridge piers urgently needs to be addressed. Precast piers have a complex load-bearing mechanism, and their design method has not been clearly determined. Fibre plastic hinge theory can satisfactorily analyse the seismic performance of precast piers. In this study, the seismic performance of precast piers is analysed through numerical simulation of pier columns based on the pseudostatic testing of a set of existing precast piers and combined with fibre plastic hinge theory. The results show the following: With reasonable constructional measures, precast piers connected by grouted sleeves indeed have seismic performance similar to that of cast-in-place components. Finite-element programs can be employed to simulate the mechanical properties of steel rebars before yielding well but not those after yielding or under fatigue. When fibre plastic hinges are used for finite-element analysis, if the fibre cross-section is reasonably divided, the length of the plastic hinge has little influence on the results; otherwise, too densely distributed plastic hinges may lead to nonconvergence of the results in a later working condition. The plastic hinge method recommended in this paper, especially the sectional fibre-cross-section division method, can obtain the plastic hinge performance state, it can help save the test cost and make up for the shortage of test data.

Dorsoventral gradient hydrogel fiber actuators visualized by AIEgen-conjugated nanoparticles

Fiber-shaped actuators made of hydrogels, inspired by plant tendrils, enable large motion and generate more pervasive automation in soft-robotics. However, replicating dorsoventral gradients of plant tendrils in hydrogel fibers remains challenging and unexplored. Herein, we demonstrate a Marangoni flow-induced self-organization of cellulose nanocrystals (CNCs) to construct a dorsoventral gradient network within a single continuous hydrogel fiber allowing helically programmed actuation that mimics plant coiling. Our approach harnesses migration-sedimentation assembly of CNCs in thermosensitive hydrogel precursor solution in the tubing that gradually photocrosslinked to produce monolithic fiber actuators rather than assembly of individual layers with dissimilar swelling properties. In situ fluorescence technology assisted by aggregation-induced emission luminogens (AIEgens) reveals the localization of CNCs in the hydrogel fiber as well as the interaction of CNCs with the gel matrix. The CNCs get arranged in a dorsoventral gradient fashion along the cross-section of hydrogel fibers due to the synergistic effect of gravity and surface tension. The AIE-assisted visualization of the particle positioning and local microenvironment for gradient hydrogel fibers offers advanced and universal characterization technique for nanocomposite hydrogel materials.

Intrinsic Mitochondrial Function Impacts the Outcomes of Metformin Treatment on Skeletal Muscle Mitochondrial Morphology in Aged Rat

Aging is the main risk factor for many costly, irreversible, and comorbid chronic diseases. The anti‐diabetic drug Metformin is being considered as an anti‐aging treatment although little is known about its effects in healthy individuals. Previous data from our lab suggest that metformin is beneficial to individuals that are relatively insulin resistant and may be detrimental to those who are insulin sensitive. We aimed to understand how intrinsic function of mitochondria affects metformin treatment outcomes in skeletal muscle. We hypothesized that the effects of metformin on skeletal muscle mitochondrial morphology and remodeling will differ based on intrinsic mitochondrial function. To test our hypothesis, we used the High‐Capacity Runner/Low‐Capacity Runner (HCR/LCR) rat model system which comprises two selectively bred lines of genetically heterogeneous rats that diverge for exercise capacity, cardiovascular risk factors, lifespan, and healthspan. In drinking water, we treated six HCR and four LCR male rats (age 18 months) with a dose of 100 mg/kg/day metformin for a week, followed by three weeks of 200 mg/kg/day. We included HCR and LCR control groups (n=5) for a total of four groups. A week prior to sacrifice, we initiated deuterium oxide (D2O) labeling to assess protein turnover and electroporated DNA constructs that encode for mitochondrial matrix‐targeted YFP and tdTomato‐tagged TOM20, a protein located on the mitochondrial outer membrane. We analyzed protein turnover in hindlimb muscles using GC‐MS, and prepared histological sections of the Tibialis Anterior (TA) muscle for further analysis of mitochondrial morphology. Normalized to tibial length, the mass of the gastrocnemius (‐16.6%) and plantaris (‐20.8%) muscles were lower in metformin treated HCR rats compared to untreated, while the normalized mass of the TA muscle was lower in both HCR (‐15%) and LCR (‐20.1%) metformin treated rats compared to control. There were no significant differences in mean fiber cross sectional area (CSA) of the TA muscle. We detected no significant differences in bulk protein synthesis of both the myofibrillar and mitochondrial fractions of the TA, gastrocnemius, and soleus muscles. The number of mitochondrial branches observed in a cross section of TA fibers from metformin treated LCR rats were 30.5% lower compared to control LCR rats. However, mean CSA of each mitochondrial branch in metformin treated LCR rats increased by 82.8% compared to control LCR rats, which, together with the decrease in branch number, resulted in maintenance of the cumulative mitochondrial CSA in each fiber. Analysis based on mitochondrial sub‐populations showed that the subsarcolemmal mitochondrial population was more impacted than intermyofibrillar mitochondria. There were no significant differences in mitochondrial morphology in control vs metformin treated HCR rats. Our data supports our hypothesis that metformin has differential effects in skeletal muscle based on intrinsic mitochondrial function prior to treatment. Additional studies are needed to determine what impact these disparities have on the aging process.

Anisotropic tribological behavior of LSI based 2.5D needle-punched carbon fiber reinforced Cf/C–SiC composites

Cf/C–SiC composites were fabricated via liquid silicon infiltration with 2.5D needle-punched carbon fiber reinforced Cf/C composites. The effect of surface topography and carbon content of the Cf/C–SiC composites on the tribological properties was researched by the ball-on-disk reciprocating tribometer. The results indicate that different fiber layers and cross-section of the composites have various surface topography and show significant differences in the friction and wear properties. By the wear morphology and model analyses, the reason for the tribological anisotropy of the composites is that the distribution of carbon and SiC phases in the composites are inhomogeneous caused by the difference of the carbon fiber orientation and the relative content in each layer. Moreover, the wear rate of the short-cut fiber web layer was the lowest and there is an obvious linear decrease in coefficient of friction with increase of carbon content. The present work explains why the tribological properties of the composites are inconsistent and provides a way to adjust the friction properties of composite materials by optimizing the friction surface.

Melanocytic Nevus With Elastophilic Features.

In dermal melanocytoses such as blue nevus or nevus of Ota, an ultrastructural study has demonstrated an intimate relationship between the dendritic melanocytes and the dermal elastic fibers with elongated cytoplasmic processes of the melanocytes aligning lengthwise along the axis of the elastic fibers in longitudinal sections and encircling the elastic fibers in cross-sections. Such a close arrangement has not been reported in common melanocytic nevi. The current case described a similar arrangement between the melanocytes and the dermal elastic fibers in a usual intradermal melanocytic nevus. Of note, as the melanocytes matured with descent, the deep melanocytes were arranged in single cells embracing the elastic fibers, imparting a signet-ring cell/phagocytosis appearance. A Verhoeff-van Gieson stain showed hypertrophy of the melanocyte-associated elastic fibers compared with the elastic fibers in the dermal background, suggesting a paracrine or juxtracrine interaction between the melanocytes and the dermal cellular components. Because of the distinctive affinity of the melanocytes to the dermal elastic fibers in this melanocytic lesion, the term melanocytic nevus with elastophilic features is suggested for this peculiar melanocytic variant.

Experimental study and simulation of non-crimp 3D orthogonal composite shafts during torsional load

Non-crimp 3D orthogonal fabrics are high-tech textiles with three sets of orthogonal yarns. 3D composites reinforced by this fabric have a high performance and wide usages due to their structure. This study attempted to investigate the torsional behavior of Glass/epoxy composite rods reinforced by 3D fabrics experimentally and numerically. Accordingly, three different 3D weaves, including low-density and high-density non-crimp 3D orthogonal, and braid-pultruded fabrics were tested by a torsion tester machine. The results showed that non-crimp 3D orthogonal composites, especially those with a higher density, had better torsional properties than the others, due to the square cross-section and perpendicular fiber involvement in all directions. Optimal torsional properties were obtained for the high-density non-crimp 3D orthogonal composite with the lower void content. Also, a python code was developed to simulate the torsional behavior of the rod composite in macro-scale based on the geometry of the unit cell and the mechanical constants obtained from the meso-scale.

Critical investigation on the effect of fiber geometry and orientation on the effective mechanical properties of fiber-reinforced polymer composites

In this study, finite element method is used to investigate the effect of combined geometry and orientation of the fiber on the elastic properties of fiber-reinforced composites. The finite element models were developed using COMSOL Multiphysics. Representative volume elements consisting of circular, square and elliptical cross-section of fibers were used in the case of combined geometry while 0°, 15°, 30°, 45°,60°, 75°, 90° and 135° were angles considered for the fiber orientation. Results from the study show that the combined geometry and fiber orientation angle has significant effect on the performance of fiber reinforced composites.

High sensitivity sensor based on mode interference of fiber arc-shaped misaligned welding structure for strain and torsion sensing

We propose a compact and ultrasensitive all-fiber Mach–Zehnder interferometer sensor based on an arc-shaped misaligned structure that can measure strain and torsion sensing. The structure utilizes a single-mode fiber and was fabricated in an optical fiber fusion splicer through simple discharge and fusion splicing steps. The experimental and theoretical investigations of its response revealed an optimal strain sensitivity of up to ~267.17 pm /με¯. In addition, the maximum torsion sensitivities in the clockwise and counterclockwise rotation directions of the fiber cross section were ~ − 1.528 dB/(rad/cm) and ~1.2191 dB/(rad/cm), respectively. Further, the proposed device exhibited low temperature cross sensitivity. Therefore, this single-mode-fiber based core-cladding modal interferometer has great potential in the field of photoelectric sensing due to multiple advantages such as compact size, easy fabrication process, low cost, etc.

A computationally efficient approach for generating RVEs of various inclusion/fibre shapes

A computationally efficient method for generating virtual periodic representative volume element (RVE), capable of handling arbitrary inclusion shapes, is developed. A universal collision/overlap detection and repair method is proposed, where each inclusion shape is represented as a union of n-Spheres (UnS). A constrained optimization problem is formulated and solved to remove inclusion overlaps; a closed-form solution is derived for calculating the degree of inclusions overlap and its gradient vector with respect to inclusion position. RVE generation is illustrated with circular, spherical, four non-circular and four non-spherical inclusion shapes. Computational efficiency is demonstrated using an elaborate RVE generation time study. The generated RVEs are evaluated using various statistical metrics; results confirm the random distribution of inclusions. Effective properties of RVEs, representing unidirectional composites, are determined using homogenization with various fibre cross-section shapes; obtained mechanical properties have shown transverse isotropy.

Intensity-demodulated fiber-optic vector magnetic field sensor based on fiber-optic evanescent field

A high-sensitivity intensity-demodulated fiber-optic evanescent field sensor is proposed for vector magnetic field measurement. The structure was fabricated by bending a section of single mode fiber into a U shape under the flame of alcohol burner, and then coated with magnetic fluid. By bending the fiber into a U shape, a non-centrosymmetric fiber-optic evanescent field is distributed on the cross section of fiber. Combing with the magnetic-field-dependent anisotropy of magnetic fluid, a high intensity sensitivity of 2.481 dB/mT and a high direction sensitivity of 0.182 dB/° were obtained. Due to the simple structure, high sensitivity and low cost, the proposed fiber-optic sensor has potential application in the vehicle navigation, aviation, and biomedical fields.

Thermo-optical numerical modal analysis of multicore fibers for high power lasers and amplifiers

Lasers for modern industrial and research applications are required to provide a high average beam power and at the same time be reliable, efficient, and compact. Rare-earth doped single-mode fiber lasers are the most promising solution. Large mode area fibers are effectively used to reduce nonlinear effects and scaling up the beam power which is now bounded by thermal effects. A new cutting-edge approach to the issue involves the use of Multi-Core Fibers (MCFs), coherently combining several lower power beams into a higher power one, and thus pushing the threshold of nonlinearities and transverse mode instabilities to higher power. The amplification process involves heat generation in the doped cores due to quantum defect, which propagates radially and creates a temperature gradient across the fiber cross-section. Even though the cores are optically uncoupled, the refractive index gradient due to thermo-optical effects could cause cross-talk and core mode coupling. In this work, we numerically analyze the performances of 9-core MCFs for high power fiber lasers by taking into account the coupling and bending effects due to the heat load generated by the quantum defect between pump and laser radiation. MCFs show very low sensitivity to heat load and bending, with effectively single-mode behaviour up to 15 μm core diameter (effective area 181 μm2) and down to 35 μm pitch.

Melt-Spun, Cross-Section Modified Polycaprolactone Fibers for Use in Tendon and Ligament Tissue Engineering

Tissue Engineering is considered a promising route to address existing deficits of autografts and permanent synthetic prostheses for tendons and ligaments. However, the requirements placed on the scaffold material are manifold and include mechanical, biological and degradation-related aspects. In addition, scalable processes and FDA-approved materials should be applied to ensure the transfer into clinical practice. To accommodate these aspects, this work focuses on the high-scale fabrication of high-strength and highly oriented polycaprolactone (PCL) fibers with adjustable cross-sectional geometry and degradation kinetics applying melt spinning technology. Four different fiber cross-sections were investigated to account for potential functionalization and cell growth guidance. Mechanical properties and crystallinity were studied for a 24-week exposure to phosphate-buffered saline (PBS) at 37 °C. PCL fibers were further processed into scaffolds using multistage circular braiding with three different hierarchical structures. One structure was selected based on its morphology and scaled up in thickness to match the requirements for a human anterior cruciate ligament (ACL) replacement. Applying a broad range of draw ratios (up to DR9.25), high-strength PCL fibers with excellent tensile strength (up to 69 cN/tex) could be readily fabricated. The strength retention after 24 weeks in PBS at 37 °C was 83–93%. The following braiding procedure did not affect the scaffolds’ mechanical properties as long as the number of filaments and the braiding angle remained constant. Up-scaled PCL scaffolds resisted loads of up to 4353.88 ± 37.30 N, whilst matching the stiffness of the human ACL (111–396 N/mm). In conclusion, this work demonstrates the fabrication of highly oriented PCL fibers with excellent mechanical properties. The created fibers represent a promising building block that can be further processed into versatile textile implants for tissue engineering and regenerative medicine.

Clinical and histopathological features of conjunctival "Teddy bear" granuloma: A case series.

To describe the clinical features, histopathological findings, and prognosis of conjunctival Teddy bear granuloma (TBG) diagnosed in a Mexican ophthalmologic referral center in a period of 64 years. We reviewed clinical and histopathological material from all patients with documented conjunctival TBG. Patient's age, gender, location, clinical signs and symptoms, duration, treatment and, specimen size, were evaluated. Formalin-fixed paraffin embedded 5 microns hematoxylin-eosin stained slides and periodic acid-Schiff special stain as well as examination under polarized light microscopy were performed in all cases. A total of 5 conjunctival TBG were collected. The ages of the patients ranged between 2 and 11 with a mean of 6 years. Female to male ratio was 4:1. The right inferior fornix was involved in 4 cases (80%) with clinical diagnosis of conjunctival mass of unknown etiology. Treatment consisted of surgical removal by slit-lamp biomicroscopy (3 cases) and in the operating room (2 cases). No complications were informed in a short follow-up period. Histopathologically, numerous cross-sections of synthetic and non-synthetic fibers surrounded by multinucleated foreign body giant cells, epithelioid histiocytes, lymphocytes, plasma cells and sparse neutrophils were seen. Polarization light microscopy demonstrated numerous birefringent colorful foreign fibers. The follow-up period of the patients ranged between 1 and 32 weeks with a mean of 10 weeks. Most patients with TBG are children with vague, non-specific symptoms troubling precise clinical diagnosis. Treatment of choice involves surgical excision of the foreign body granuloma followed by topical corticosteroids. All surgical specimens obtained must be sent for histopathological examination. Special awareness is recommended during COVID-19 pandemic lockdown to prevent potential exposure to fibers that may cause conjunctival TBG.

Effect of genotype and sex on carcase composition, physicochemical properties, texture and microstructure of meat from geese after four reproductive seasons

ABSTRACT 1. The objective of this study was to compare carcase weight and composition and meat quality traits of Landes, Slovak White and Kuban geese after four reproductive seasons. A total of 42 goose carcases (seven males and seven females from each breed) were assessed. 2. After four reproductive seasons, the breeds differed in eviscerated carcase weight. Slovak White geese showed more breast muscle with a cooking loss, whereas Kuban geese had a higher percentage of neck and carcase discards compared to the other breeds. The breeds differed in the chemical composition of breast and leg muscles, except for collagen in breast muscles and protein in leg muscles. 3. Regardless of breed, males had heavier carcase weight and higher breast muscle, leg muscle, neck and wings and lower percentages of skin with subcutaneous fat and abdominal fat relative to body weight compared to females. Sex had a significant effect on the fat and salt content, meat lightness, most textural characteristics and endomysium thickness of breast muscle. The same differences in leg muscles for chemical composition (except for protein percentage) and lightness were recorded. 4. Breed x sex interactions were significant for the proportion of leg muscle, chemical composition of breast and leg muscles (except for leg protein content), muscle fibre cross-sectional area and fibre perimeter of pectoralis major muscle. 5. The results showed that the carcases and meat of the goose breeds after four reproductive seasons were suitable for consumers and meat processors, due to favourable composition, high nutritive value and good technological properties.

Phase-dependent local brain states determine the impact of image-guided transcranial magnetic stimulation on motor network electroencephalographic synchronization.

Recent studies have synchronized transcranial magnetic stimulation (TMS) application with pre-defined brain oscillatory phases showing how brain response to perturbation depends on the brain state. However, none have investigated whether phase-dependent TMS can possibly modulate connectivity with homologous distant brain regions belonging to the same network. In the framework of network-targeted TMS, we investigated whether stimulation delivered at a specific phase of ongoing brain oscillations might favour stronger cortico-cortical (c-c) synchronization of distant network nodes connected to the stimulation target. Neuronavigated TMS pulses were delivered over the primary motor cortex (M1) during ongoing electroencephalography recording in 24 healthy individuals over two repeated sessions 1month apart. Stimulation effects were analysed considering whether the TMS pulse was delivered at the time of a positive (peak) or negative (trough) phase of μ-frequency oscillation, which determines c-c synchrony within homologous areas of the sensorimotor network. Diffusion weighted imaging was used to study c-c connectivity within the sensorimotor network and identify contralateral regions connected with the stimulation spot. Depending on when during the μ-activity the TMS-pulse was applied (peak or trough), its impact on inter-hemispheric network synchrony varied significantly. Higher M1-M1 phase-lock synchronization after the TMS-pulse (0-200ms) in the μ-frequency band was found for trough compared to peak stimulation trials in both study visits. Phase-dependent TMS delivery might be crucial not only to amplify local effects but also to increase the magnitude and reliability of the response to the external perturbation, with implications for interventions aimed at engaging more distributed functional brain networks. KEY POINTS: Synchronized transcranial magnetic stimulation (TMS) pulses with pre-defined brain oscillatory phases allow evaluation of the impact of brain states on TMS effects. TMS pulses over M1 at the negative peak of the μ-frequency band induce higher phase-lock synchronization with interconnected contralateral homologous regions. Cortico-cortical synchronization changes are linearly predicted by the fibre density and cross-section of the white matter tract that connects the two brain regions. Phase-dependent TMS delivery might be crucial not only to amplify local effects but also to increase the magnitude and reliability of within-network synchronization.

Characteristics of a rectangular channel sensor based on evanescent field enhanced photonic crystal fiber

A miniaturized, rectangular-channel photonic crystal fiber (RC-PCF) high-sensitivity sensing scheme is proposed for high-refractive-index liquid analysis. The designed PCF is polished and features an open rectangular channel in the upper-middle part of the fiber cross-section, which facilitates the efficient flow of the sample liquid. The design utilizes the merit of photonic crystal array and the operability of external sensing. Gold is chosen as the plasma material because of its chemical stability and biocompatibility in a liquid environment. To obtain high sensitivity, the effect of the sample liquid height in the channel on the sensing performance is investigated. Numerical results show that the maximum wavelength sensitivity and amplitude sensitivity of the sensor is 28,000 nm/RIU (refractive index unit) and − 1266.5 R I U − 1 with a liquid analyte height of 100% of the channel height. The maximum wavelength sensitivity increases from 28,000 to 42,000 nm/RIU when the gold film thickness decreases from 30 nm to 20 nm. Due to the sensor’s simple structure and high sensitivity, it will have potential applications in the detection of high-refractive-index samples in biology, medicine, and chemistry.

Femtosecond laser auto-positioning direct writing of a multicore fiber Bragg grating array for shape sensing.

A multicore fiber Bragg grating (MC-FBG) array shape sensor is a powerful tool for a variety of applications. However, the efficient fabrication of high-quality MC-FBG arrays remains a problem. Here, we report for the first time, to the best of our knowledge, a new method of directly writing FBG arrays in a seven-core fiber (SCF) through the protective coating using femtosecond laser auto-positioning point-by-point technology, which is accomplished by image recognition and micro-displacement compensation. An MC-FBG array consisting of 140 individual FBGs with a grating length of 2 mm was successfully inscribed into seven cores of a 440 mm-long SCF. Each core contained 20 wavelength-division-multiplexed (WDM) FBGs with wavelengths ranging from 1522.11 nm to 1579.28 nm. In other words, the MC-FBG array consisted of 20 WDM nodes with an interval of 2 cm along the fiber, and each node contained seven identical FBGs integrated in parallel into the fiber cross-section. Moreover, the fabricated MC-FBG array exhibited a strong orientation dependence in bend sensing, with a maximum sensitivity of 55.49 pm/m-1. Subsequently, 2D and 3D shape sensing were demonstrated using the fabricated MC-FBG array, with maximum reconstruction errors per unit length of 4.51% and 10.81%, respectively. Hence, the MC-FBG arrays fabricated using the proposed method are useful in many applications, such as posture monitoring, smart robotics, and minimally invasive surgery.

Identification of Deep Brain Stimulation Targets for Neuropathic Pain After Spinal Cord Injury Using Localized Increases in White Matter Fiber Cross Section

ObjectivesThe spinal cord injury (SCI) patient population is overwhelmingly affected by neuropathic pain (NP), a secondary condition for which therapeutic options are limited and have a low degree of efficacy. The objective of this study was to identify novel deep brain stimulation (DBS) targets that may theoretically benefit those with NP in the SCI patient population. We hypothesize that localized changes in white matter identified in SCI subjects with NP compared to those without NP could be used to develop an evidence-based approach to DBS target identification. Materials and MethodsTo classify localized neurostructural changes associated with NP in the SCI population, we compared white matter fiber density (FD) and cross section (FC) between SCI subjects with NP (n = 17) and SCI subjects without NP (n = 15) using diffusion-weighted magnetic resonance imaging (MRI). We then identified theoretical target locations for DBS using fiber bundles connected to significantly altered regions of white matter. Finally, we used computational models of DBS to determine if our theoretical target locations could be used to feasibly activate our fiber bundles of interest. ResultsWe identified significant increases in FC in the splenium of the corpus callosum in pain subjects when compared to controls. We then isolated five fiber bundles that were directly connected to the affected region of white matter. Our models were able to predict that our fiber bundles of interest can be feasibly activated with DBS at reasonable stimulation amplitudes and with clinically relevant implantation approaches. ConclusionsAltogether, we identified neuroarchitectural changes associated with NP in the SCI cohort and implemented a novel evidence-driven target selection approach for DBS to guide future research in neuromodulation treatment of NP after SCI.

A cleaner goatskin preservation with leaf paste and powder: An approach for salinity remediation in tannery wastewater

In this study, a new skin preservation method using Clerodendrum viscosum leaf has been explored to find out an efficient alternative to the most popular salted preservation in leather processing. The effectiveness of the preservation systems was evaluated on a regular interval by measuring parameters like organoleptic properties, moisture content, bacterial count, and hydrothermal stability of preserved skins. After preservation, the goatskins were processed into crust leather and compared with different strength properties of corresponding conventionally preserved skins. The cross-sectional fiber structure was found undamaged by assessing scanning electron microscopy images. The salt-free preservation method in this study could reduce the total dissolved solids and chloride in the soaking liquor by 74% and 98% respectively. In contrast, the less-salt preservation method could reduce the total dissolved solids and chloride by 57% and 59%respectively. The overall results of this study revealed that the leaf of Clerodendrum viscosum plant can be used to preserve skin. The strength properties of the produced leathers also fulfilled the requirements of shoe upper leather. The proposed Eco-friendly preservation techniques are found comparable to a great extent with the traditional salt curing approaches. So, these can be used as viable alternative options for skin preservation in the leather processing industries.

Infrared laser exposure in combination with branchedchain amino acid stimulates physiological adaptation of skeletal muscles

Laser exposure stimulates cell proliferation and tissue repair. Branched-chain amino acids (BCAA) are widely used in sports medicine as a stimulator of anabolic processes. However, there is no evidence of the effect of combined laser and BCAA application on skeletal muscle morphometric characteristics during exercise in the training process.Purpose: to study the effect of infrared laser exposure in combination with amino acid at myosatellitocytes and skeletal muscle myocytes during swimming training.Material and methods. The experiment was conducted on 30 Wistar rats: Group 1 – intact, Group 2 – dynamic control (trainings with endurance swimming), Group 3 – trainings and BCAA, Group 4 – trainings and laser exposure at hip muscles (970 nm, 1 W, 60 s), Group 5 – combined exposure to laser and BCAA. Trainings were three times a week for 6 weeks; laser session was after each training. Samples of the bipedal thigh muscle were fixed with formalin; histological sections were stained with hematoxylin-eosin. The morphometric analysis of the digital image of objects with statistical processing by Mann – Whitney method was made.Results. Laser exposure combined with BCAA during trainings increased the nuclei area and the number of myosatellites and myocytes; it also enlarged the cross section of muscle fibers which was more pronounced if to compare with isolated laser irradiation of the muscle or BCAA.Conclusions. Infrared laser exposure in combination with branched-chain amino acids effectively stimulates regeneration due to hyperplasia and hypertrophy of skeletal muscular tissue, thus providing physiological adaptation in the training process.