Arrangement Of Muscle Fibers Research Articles

Rethinking the physiological cross-sectional area of skeletal muscle reveals the mechanical advantage of pennation

The shape of skeletal muscle varies remarkably—with important implications for locomotor performance. In many muscles, the fibres are arranged at an angle relative to the tendons’ line of action, termed the pennation angle. These pennate muscles allow more sarcomeres to be packed side by side, enabling the muscle to generate higher maximum forces for a given muscle size. Historically, the physiological cross-sectional area (PCSA) has been used to capture both the size and arrangement of muscle fibres, and is one of the best predictors of a muscles capacity to produce force. However, the anatomical and mechanical implications of PCSA remain ambiguous as misinterpretations have limited our ability to understand the mechanical advantage of pennate muscle designs. We developed geometric models to resolve the mechanistic and functional impacts of pennation angle across a range of muscle shapes and sizes. Comparisons among model predictions and empirical data on human lower limb muscles demonstrated how a pennate arrangement of fibres allows muscles to produce up to six times more isometric force when compared with non-pennate muscles of the same volume. We show that in muscles much longer than thick, an optimal pennation angle exists at which isometric force is maximized. Using empirically informed geometric models we demonstrate the functional significance of a pennate muscle design and provide a new parameter, pennation mechanical advantage, which quantifies this performance improvement.

Effect of precursor amino acids for carnosine synthesis on breast fiber microstructures and myofiber differentiation-related gene expression in slow-growing chicken.

: The effects of carnosine synthesis on the structural and microstructural determinants of meat quality have not been studied to date. Therefore, this study aimed to investigate the effect of supplementation with carnosine synthesis precursors on the characteristics and microstructure of breast muscle fibers in slow-growing Korat chickens (KR). : Slow-growing KR were fed a non-supplemented commercial diet (control group) or a commercial diet supplemented with 1.0% β-alanine, 0.5% L-histidine, or a combination of both 1.0% β-alanine and 0.5% L-histidine. At 10 weeks, KR were slaughtered, and the breast muscle was collected. Samples were fixed and extracted to study the microstructure, fat level, and porosity of the meat using X-ray and scanning electron microscopy, and real-time polymerase chain reaction was performed to analyze the expression of genes related to myofiber differentiation. : L-histidine supplementation significantly altered myofiber diameter and muscle fiber density and compactness by regulating muscle fiber-type differentiation via carnosine synthase (CARNS1) and myocyte enhancer factor 2C (MEF2C) expression, as well as myogenic differentiation antigen (MyoD) and myogenic regulatory factor 5 (Myf5) expression. While excess L-histidine potentially stimulated CARNS1 to modify muscle fiber arrangement and tenderness in breast meat, dietary β-alanine supplementation alone or in combination with L-histidine supplementation induced a relatively less remarkable but not significant (p<0.05) effect on the breast meat characteristics studied. : Interestingly, the combination of β-alanine and L-histidine supplementation had no effect on meat microstructure, meat porosity, and fat content in comparison with the control group. Thus, this combination had the best selectivity for improving meat quality. However, further studies are required to clarify the effects of carnosine levels on meat processing.

An efficient and cost-effective methods framework for performing biomechanical analysis on cadaveric skeletal muscle

IntroductionThe structure and arrangement of skeletal muscle fibers is the primary determinant of muscle function. While analysis of morphologic parameters to elucidate muscle structure-function relationships dates to the 17th century, considerable variability in methodology and technique to quantify these relationships exists within the literature. Additionally, applications to assess the impact of non-typical musculoskeletal morphologies on structure-function relationships are limited. This study aims to assemble and present a practical, step-by-step framework of combined methods and techniques for efficiently analyzing biomechanical impacts of cadaveric skeletal muscles. MethodsExisting skeletal muscle biomechanical formulas and experimentally determined parameters for typical fast-acting skeletal muscle were identified in the literature. The methods framework was assembled as a stepwise protocol that includes mathematical formulas, referenced accepted values, optional steps, section breaks, suggested techniques, important notes and footnotes, and materials needed for collecting necessary measurements. Proof of concept was achieved with primary histological data and imaging, along with references to examples where the methods have been successfully applied. ResultsThe assembled framework presents an ordered process for measuring skeletal muscle parameters, calculating the maximal isometric force of a skeletal muscle, and applying that data to understand musculoskeletal mechanics. Histology data, imaging, and a summary of studies that have successfully applied the framework methods provide visual aids and validation for the methods. ConclusionsThis study presents an efficient and convenient framework of combined methods and techniques for investigators to evaluate the biomechanical impact of skeletal muscles. The practical use of this framework should optimize project efficiency and spending, increase study rigor, and minimize procedural variation across different studies. This report may serve as a foundational resource for researchers studying cadaveric muscle biomechanics, and its use especially adds translational clinical value to case analyses of non-typical musculoskeletal morphologies.

Effect of Zanthoxylum bungeanum extract on the quality and cathepsin L activity of Niuganba

Niuganba (NGB) is a traditional fermented beef product. Protease activity typically significantly affects the quality of NGB. Some natural food extracts may markedly influence NGB's protease activity and performance. This study aims to investigate the effect of Zanthoxylum bungeanum extract (ZBE) on the quality and cathepsin L activity of NGB. Following ZBE treatment, the myofibril fragmentation index (MFI), the content of TCA-soluble peptides, surface hydrophobicity, disulfide bond content, and cathepsin L activity of NGB significantly decrease. The content of free thiol groups and β-sheet significantly increases. Scanning electron microscopy (SEM) reveals that the arrangement of muscle fibers in the cross-section of NGB is more compact after ZBE treatment. The research results indicate that ZBE effectively inhibits cathepsin L activity, alleviates the degradation of myofibrillar proteins, improves the physicochemical characteristics of NGB, and enhances its structural stability.

CHARACTERISTICS OF PATHOMORPHOLOGICAL CHANGES IN HYPERTROPHIC CARDIOMYOPATHY

In hypertrophic cardiomyopathy, the walls of the ventricles of the heart continue with symmetric or asymmetric myocardial hypertrophy. Morphologically, in hypertrophic cardiomyopathy, fibrotic foci are detected based on the incorrect arrangement of myocardial muscle fibers, small coronary vessel syndrome, and myocardial hypertrophy.

#2366 Beneficial effects of TRIM33 on myokine-mediated renal function recovery in diabetic and obese mice

Abstract Background and Aims Myokines secreted from myocytes are related to improving metabolic diseases such as diabetes, obesity, and chronic kidney disease (CKD). Patients with diabetic kidney disease (DKD) have lower irisin levels, suggesting that a low level of irisin is a risk factor for the progression of CKD. However, it is not well known how myokines can alleviate metabolic kidney injury. This study aimed to investigate the effect of TRIM33, a negative regulator of TGF-β1 signaling, as a novel strategy to treat multiple metabolic complications simultaneously in the kidneys and muscles of obese db/db mice. Method For the in vivo experiment, five-week-old male db/db mice were assigned to three groups: db/m+, db/db, and db/db with TRIM33 plasmid mice. TRIM33 plasmid (40 μg/mice) was administered intraperitoneally. Serum glucose and myokine levels, urinary albumin excretion, renal and muscle morphology, and myokine expression in muscles were assessed. In vitro, C2C12 cells were cultivated with 2% horse serum and lipid insult in the absence or presence of TRIM33 plasmid and were analyzed for myocyte differentiation and myokines expression or production. Results TRIM33 treatment showed beneficial effects on tubular injury, tubulointerstitial fibrosis, mesangial expansion, renal dysfunction, variations in skeletal muscle fiber size and arrangement, skeletal muscle activity, and serum myokines levels in db/db mice. During the differentiation of C2C12 cells, myokine mRNA and protein expression and secretion were increased in TRIM33-transfected cells. Reduced levels of myokines expression and secretion in C2C12 cells with palmitate were improved by TRIM33 transfection. In coculture with HK-2 and C2C12 cells, increased EMT transition in TGF-b-treated HK-2 cells by coculture with palmitate-treated C2C12 cells was decreased in coculture with palmitate-treated C2C12 cells with TRIM33 transfection. Conclusion This study showed that TRIM33 is involved in the recovery of renal dysfunction via myokine in mice with diabetes and obesity.

Effects of collagen-based coating with chitosan and ε-polylysine on sensory, texture, and biochemical changes ofrefrigerated Nemipterus virgatus fillets.

In order to evaluate the effects of chitosan, ε-polylysine, and collagen on the preservation properties of refrigerated Nemipterus virgatus, samples were tested with different treatments for 10 days, namely chitosan, ε-polylysine and collagen (CH + ε-PL + CA), chitosan and ε-polylysine (CH + ε-PL), chitosan and collagen (CH + CA), ε-polylysine and collagen (ε-PL + CA), and the uncoated sample (CK). The results demonstrated that the bio-coating exhibited better preservation effects. The CH + ε-PL + CA, CH + ε-PL, CH + CA, ε-PL + CA treatments could significantly inhibit bacterial growth and retard the increase of total volatile base nitrogen (TVB-N), 2-thiobarbituric acid (TBA), K-value, and total viable counts (TVC) in N. virgatus fillets. The pH of all samples decreased and reached its lowest value on day 6, then increased significantly at the end of the experiment (p < .05). Water-holding capacity (WHC) of all the groups decreased continuously throughout storage, and CK reached 66.03% on day 6, which is significantly lower than CH + ε-PL + CA, CH + ε-PL, CH + CA, and ε-PL + CA (p < .05). On the contrary, the sensory scores of CH + ε-PL + CA, CH + ε-PL, CH + CA, and ε-PL + CA were significantly higher than the control, and the score of CH + ε-PL + CA (p < .05) was the best among all the groups. In terms of texture, CH + PL + CA also showed less cell shrinkage and tighter muscle fiber arrangement compared to other treatments. To sum up, the CH + PL + CA bio-coating proved to be a promising method for maintaining the storage quality of N. virgatus under refrigerated storage conditions.

Mimicking Transmural Helical Cardiomyofibre Orientation Using Bouligand-like Pore Structures in Ice-Templated Collagen Scaffolds.

The helical arrangement of cardiac muscle fibres underpins the contractile properties of the heart chamber. Across the heart wall, the helical angle of the aligned fibres changes gradually across the range of 90-180°. It is essential to recreate this structural hierarchy in vitro for developing functional artificial tissue. Ice templating can achieve single-oriented pore alignment via unidirectional ice solidification with a flat base mould design. We hypothesise that the orientation of aligned pores can be controlled simply via base topography, and we propose a scalable base design to recapitulate the transmural fibre orientation. We have utilised finite element simulations for rapid testing of base designs, followed by experimental confirmation of the Bouligand-like orientation. X-ray microtomography of experimental samples showed a gradual shift of 106 ± 10°, with the flexibility to tailor pore size and spatial helical angle distribution for personalised medicine.

Low-frequency alternating magnetic field thawing of frozen pork meat: Effects of intensity on quality properties and microstructure of meat and structure of myofibrillar proteins

The purpose of the study was to evaluate the changes in quality properties and microstructure of pork meat as well as structural variation in myofibrillar proteins (MPs) after low-frequency alternating magnetic field thawing (LF-MFT) with different intensities (1–5 mT). LF-MFT at 3–5 mT shortened the thawing time. LF-MFT treatment significantly influenced the quality properties of meat and notably improved the structure of MPs (P < 0.05), compared to atmosphere thawing (AT). Especially, among the thawing treatments, LF-MFT-4 (LF-MFT at 4 mT) had the lowest values of thawing loss and drip loss, and the least changes in the color and myoglobin content. Regarding the results of rheological properties and micrographs, an optimal gel structure and a more compact muscle fiber arrangement formed during LF-MFT-4. Moreover, LF-MFT-4 was beneficial for improving the conformation of MPs. Therefore, LF-MFT-4 reduced the deterioration of porcine quality by protecting MPs structure, indicating a potential use in the meat thawing industry.

Underlying mechnism of electroacupuncture for treating detrusor hyperreflexia after suprasacral spinal cord injury through the PACAP-cAMP signaling pathway: 基于PACAP-cAMP信号通路研究电针治疗骶上脊髓损伤后逼尿肌反射亢进型膀胱的效应机制

ObjectiveTo elucidate the underlying mechanism and effect of electroacupuncture (EA) on the neurogenic bladder following suprasacral spinal cord injury (SSCI). A rat model of detrusor hyperreflexia after SSCI was established to examine the urodynamics, detrusor muscle tissue morphology, the protein and mRNA expression levels of pituitary adenylate cyclase activating peptide (PACAP) and its receptor PAC1R, and cyclic adenosine monophosphate (cAMP) content in the detrusor muscle with a focus on the PACAP-cAMP signaling pathway. MethodA total of 72 female SD rats were randomized into control group and sham operation group (n=12 per group) by using a random number table. The remaining 48 rats were established into the model of detrusor hyperreflexia after SSCI. After successful modeling, these rats were randomly assigned to model, EA, and EA + PACAP6-38 groups (n=12 per group). The unsuccessful modeled rats were used for exploratory observation. For the rats in EA group, “Ciliao (BL32)” “Zhongji (CV3)”, and “Sanyinjiao (SP6)” were needled and stimulated by EA. The PACAP receptor antagonist PACAP6-38 was administered intraperitoneally in the EA + PACAP6-38 group before EA, and EA was applied for seven consecutive days. After treatment, the urodynamics of the rats were analyzed, and hematoxylin and eosin staining was used to examine rat bladder detrusor tissue morphology. The expressions of PACAP-38 and PAC1R were detected by immunohistochemistry and Western blot. The mRNA expression levels of PACAP-38 and PAC1R were examined by RT-qPCR, while cAMP content was detected by ELISA. Results(1) Compared with sham operation group, it was exhibited disarray in the transitional epithelium cells of the bladder in the modeled rats. The intercellular space was significantly widened, accompanied by inflammatory cell infiltration and noticeable tissue edema. Both the bladder initial pressure and leak point pressure of the rats were higher (P < 0.01), whereas the maximum cystometric capacity and bladder compliance were lower (P < 0.01). The protein and mRNA expression levels of PACAP-38 and PAC1R in the detrusor muscle, together with the cAMP content, were lower (P < 0.05). (2) Compared with the model rats, the EA group showed reduced inflammatory response in the detrusor muscle tissue, with decreased monocyte infiltration and less severe tissue edema. The bladder smooth muscle cells exhibited increased integrity, and there was decreased cellular tissue edema, inflammatory cell infiltration, and fibroplasia. The bladder initial pressure and leak point pressure were lower (P < 0.05), while the maximum cystometric capacity and bladder compliance were higher (P < 0.01). The protein and mRNA expression levels of PACAP-38 and PAC1R in the detrusor muscle, along with the cAMP content, were higher (P < 0.05). (3) Compared to the EA group, the EA + PACAP6-38 group showed a less organized arrangement of muscle fibers in the detrusor muscle tissue, larger intercellular space, monocyte infiltration, and considerable tissue edema. The changes in bladder initial pressure and leak point pressure were not significant (P > 0.05), while the maximum cystometric capacity and bladder compliance were lower (P < 0.05). The changes in the protein and mRNA expressions of PACAP-38 within the detrusor muscle were not significant (P > 0.05), whereas the protein and mRNA expressions of PAC1R were reduced (P < 0.05), and the cAMP content within the detrusor muscle was lower (P < 0.05). ConclusionEA can ameliorate the uninhibited contractile condition of the detrusor muscle in the bladder following SSCI. By mediating the PACAP-cAMP signaling pathway, it reduces the pathological damage to the detrusor muscle, thereby improving bladder function.

The protective effects of Zhi-Gan-Cao-Tang against diabetic myocardial infarction injury and identification of its effective constituents.

Cardiovascular complications are highly prevalent in patients with diabetes. Zhi-Gan-Cao-Tang (ZGCT), a famous traditional Chinese medicine (TCM) prescription, can be used for the treatment of diabetes with cardiovascular disease complications. ZGCT is composed of nine Chinese herbs: the radix and rhizoma of Glycyrrhiza uralensis Fisch. (Gancao in Chinese, 12g), the radix of Rehmannia glutinosa Libosch. (Dihuang in Chinese, 50g), the radix and rhizoma of Panax ginseng C. A. Mey. (Renshen in Chinese, 6g), the radix of Ophiopogon japonicus (L. f.) Ker-Gawl. (Maidong in Chinese, 10g), the fructus of Ziziphus jujuba Mill. (Dazao in Chinese, 18g), the fructus of Cannabis sativa L. (Maren in Chinese, 10g), Donkey-hide gelatine (Ejiao in Chinese, 6g), the ramulus of Cinnamomum cassia Presl (Guizhi in Chinese, 9g), and the fresh rhizoma of Zingiber officinale Rosc. (Shengjiang in Chinese, 9g). Many of these Chinese herbs are also used in other systems of medicine (Japan, India, European, etc.). However, the effects and effective constituents of ZGCT against diabetic cardiovascular disease remain unclear. This study aimed to investigate the protective effect of ZGCT against diabetic myocardial infarction (DMI) injury in vivo and in vitro and to identify the effective constituents of ZGCT. The in vivo effect on DMI injury was evaluated in a DMI mouse model. The in vitro effect and effective constituent screening experiments were conducted in an H9c2 cardiomyocyte injury model induced by high glucose and hypoxia. It was found that ZGCT significantly reduced myocardial infarction size and serum lactate dehydrogenase (LDH) levels in DMI mice. Myocardial histopathological experiments showed that ZGCT alleviated the disordered arrangement and fracture of muscle fibers and cell disappearance and reduced inflammatory cell infiltration. Cellular experiments showed that ZGCT inhibited cardiomyocyte apoptosis by decreasing the expression of the proapoptotic factor Bax. In addition, it inhibited inflammatory reactions by suppressing the activation of the IκBα/NF-κB pathway and the expression of iNOS. Eight constituents from six Chinese herbs in the recipe of ZGCT were found to enhance the viability of injured cardiomyocytes, and six effective constituents played protective roles through anti-apoptotic and/or anti-inflammatory activities. In addition, one of the effective constituents, glycyrrhizic acid, was verified in vivo to have cardioprotective effect on DMI mice. The TCM prescription ZGCT protects against DMI by inhibiting cardiomyocyte apoptosis and reducing inflammatory reactions. Eight effective constituents of ZGCT were identified. This study provides a scientific basis for the clinical application of ZGCT and is valuable for quality marker research on this prescription.

Homogeneity versus inhomogeneity in muscle elastography

The hierarchal microstructure and arrangement of skeletal muscle fibers results in both anisotropy and inhomogeneity. Most elastography reconstruction methods assume homogeneity and many also assume isotropy. In this computational (finite element) and experimental (MR) elastography study we investigate the impact of assuming homogeneity as muscle architecture dimensions and property differences are varied. This analysis also takes into consideration the inherent anisotropy (transverse isotropy) created by homogenization of the fiber structure, and the added complication ofnonhomogeneous (pre-stress) boundary conditions. Specifically, the computational harmonic analysis uses a parametric sweep across 200 Hz to 2000Hz applied to 4-, 40- and 400-fiber models with the aligned fiber cross-sectional area fixed (reduced fiber diameter as fiber count increases) and comprising 50% of the circular cross-sectional area in the fixed diameter cylindrical phantom. Fiber elastic moduli two to five times that of connective tissue are considered. This phantom also undergoes tensile axial pre-loading simultaneous to elastography studies. Predicted results are compared to a homogeneous transverse isotropic model that is reached in the limit as the fiber count increases to infinity while still summing to 50% of the cross-sectional area. Selected cases, such as the 4-fiber model are also evaluated experimentally using MR elastography.

Effects of heat exposure and vitamin C intervention on oxidative stress and blood pressure changes in treadmill rats

Objective: To investigate the effect of oxidative stress caused by heat exposure on the blood pressure increase of treadmill rats and the intervention of antioxidants. Methods: In June 2021, Twenty-four healthy SD male rats were randomly divided into four groups: normal temperature feeding, normal temperature treadmill, high temperature treadmill and high temperature treadmill supplementation with vitamin C groups, 6 rats in each group. The rats run on the platform in normal temperature or heat exposure environment for 30 min in the morning and in the afternoon daily, 6 days per week. The daily vitamin C supplement dose of high temperature treadmill supplementation with vitamin C group was 10 mg/kg. BP recordings were done at the end of the week. The rat vascular lipofuscin (LF) was detected by ELISA, the rat serum nitric oxide (NO) was detected by nitrate reductase method, the serum malondialdehyde (MDA) was detected by thibabituric acid method, the serum glutathione peroxidase (GPx) and superoxide dismutase (SOD) were detected by chemiluminescence method, and the serum catalase (CAT) was detected by ammonium molybdate method. The total antioxidant capacity (T-AOC) of serum was measured by iron reduction/antioxidant capacity method, and the content of nuclear erythroid 2-related factor 2 (Nrf2) in vascular tissue was measured by Western blot. The intra-group mean was compared by repeated measurement analysis of variance, and the inter-group mean was compared by single-factor analysis of variance and post-event LSD-t test. Results: Compared with the previous time point, the systolic BP and diastolic BP of the high temperature treadmill group were significantly increased at 7, 14 and 21 d, and decreased at 28 d which were higher than the initial level (P<0.05), and the systolic BP and diastolic BP values at each experimental time point were significantly higher than those of normal temperature treadmill group (P<0.001). The changes of thickening of the artery wall, no smoothing of the endodermis and irregular arrangement of muscle cells in high temperature treadmill group were observed. Compared with the normal temperature treadmill group, the content of MDA in serum, and LF in vascular tissue were significantly increased, the activities of SOD, CAT, T-AOC, the content of NO in serum, and the expression of Nrf2 in vascular tissue were significantly decreased in high temperature treadmill group (P<0.05). Compared with the high temperature treadmill group, the systolic BP and diastolic BP values at 7, 14, 21 and 28 d, the content of serum MDA and LF in vascular tissue were significantly decreased, the activities of CAT and T-AOC, and the expression of Nrf2 in vascular tissue significantly increased (P<0.05), the histopathological changes of the artery wall improved in high temperature treadmill supplementation with vitamin C group. Conclusion: Heat exposure has effect on oxidative stress, which may be related to the increase of BP. Vitamin C as an anti-oxidative enhancer can prevent those negative effects, which could alleviate the pathological changes of vessel intima in heat-exposed rats. And the Nrf2 may be a regulated factor to vascular protection.

Особенности строения четырехглавой мышцы бедра цыплят-бройлеров кросса «Смена-9» при различных рационах кормления

The article presents the results of studies of the weight characteristics of broiler chickens of the Smena-9 cross, as well as the morphological features of the quadriceps femoris in these birds on the 35th day of postembryonic ontogenesis with various feeding diets. The work was implemented within the framework of the thematic task plan for the implementation of research works under the state order of the Ministry of Agriculture of the Russian Federation (Agreement No. 082-03-2023- 238 dated 30.01.2023) on the topic: "Development of theoretical foundations and methodology for the practical use of morphological criteria in assessing the quality and safety of poultry products." It is shown that against the background of the use of feed additives, growth processes are stimulated, which is manifested by an increase in the weight of chickens. At the same time, the microstructure of the rectus head of the quadriceps femoris of birds of the control and experimental groups, while maintaining the general plan of structure (the presence of muscular and connective tissue components, bundle organization), becomes unequal. In the experimental group using prebiotic (D1), the loosest packing of muscle fibers in the bundle structure was noted due to the significant development of endomysium and perimysium, which is also characteristic of control samples. In the experimental groups using probiotic and sorbent (D2 and D3, respectively), a dense arrangement of muscle fibers in the bundle structure was revealed, as well as a denser packing of myofibrils in the structure of muscle fibers compared with the control and experimental group D1. At the same time, thickening of the perimisium in the groups and the development of white adipose tissue in it were noted, which may correspond to an improvement in the taste qualities of poultry meat. The obtained results can be used as morphological criteria in the scheme of assessing the quality and safety of meat products. Data on the structural organization of the quadriceps muscle of the new domestic cross expand the theoretical base in the field of the myology of farm birds, including in terms of identifying morphological signs of the realization of genetic potential against the background of the use of different feeding diets in chicken rearing technology, which allows us to quickly assess the effectiveness of chicken rearing technology and predict an increase in productivity.

Muscle architecture a new dimension of talent identification: A mini review

Talent Identification in the field of exercise science is growing exponentially, where muscle is considered as most reliable method for determining muscle fiber type and selecting sports activity accordingly. Muscle architecture a new fiber type determination technique is now in trend, which refers to the macroscopic arrangement of muscle fibres that influences a muscle's mechanical function. Previous research has shown a relationship between muscle architecture (such as fascicle length, muscle thickness, and pennation angle) and muscle fibre types (e.g. slow twitch fibres and fast twitch fibers). This small review attempts to briefly discuss how muscle architecture has been investigated in the realm of sport/exercise performance, as well as how various muscle fibre types have varied muscle architecture characteristics.

Effect of electroacupuncture of "Weizhong" (BL40) on iron metabolism disorder in rats with lumbar multifidus muscle injury

To observe the effect of electroacupuncture (EA) of "Weizhong" (BL40) on the disorder of iron metabolism and the level of oxidative stress after lumbar multifidus muscle injury (LMMI), so as to explore its mechanisms underlying promoting the repair of LMMI. Male SD rats were randomly divided into normal, model and EA groups (6 rats in each group). The LMMI model was established by injecting 0.5% bupivacaine (BPVC) solution (400 μL) into the lumbar multifidus muscle with the syringe-needle close to the spinous process (L4-L5). Twenty-four hours after successful establishment of the model, EA (2 Hz/15 Hz, 2 mA) was applied to bilateral BL40 for 30 min, once a day for 2 days. Histopathological changes of the multifid muscle were observed under microscope after H.E. staining, and the iron granules in the multifid muscle tissue observed after Prussian blue staining. The expression of glutathione synthase (GSS) was detected by Western blot, and the expressions of iron regulatory protein 1 (IRP1), ferroportin (Fpn), ferritin heavy chain 1 (FTH1, iron metabolism-related proteins) and gluta-thione peroxidase 4 (GPX4, functions in protecting cells against detrimental lipid peroxidation and governing a novel form of regulated necrotic cell death, called ferroptosis) mRNAs were detected by quantitative real-time PCR. The contents of glutathione (GSH) and malondialdehyde (MDA) were measured by biochemical methods. H.E. staining showed large areas of necrosis and breakage of muscle fibers, disordered arrangement of muscle fibers, widened muscle cell space, accompanying with a large number of inflammatory cell infiltration in the multifidus muscle tissue of the model group, which was relatively milder in the EA group. Outcomes of Prussian blue staining showed that compared with the normal group, there were more iron particles in the multifidus muscle tissue and enlarged muscle fiber gaps, which was also milder in the EA group. Compared with the normal group, the expression level of IRP1 mRNA and content of MDA were significantly increased (P<0.001), the expression levels of Fpn, FTH1 and GPX4 mRNAs and GSS protein, and the content of GSH were considerably decreased (P<0.001) in the model group. In comparison with the model group, the increase of IRP1 mRNA expression and MDA content, as well as the decrease of Fpn, FTH1 and GPX4 mRNAs expressions and GSH content were reversed in the EA group (P<0.001,P<0.05,P<0.01). EA of BL40 has a protect effect in BPVC-induced injury of lumbar multifidus muscle in rats, which may be related to its functions in improving iron metabolism to reduce oxidative damage by regulating expression of IRP1, Fpn and FTH1.

Comparison of Imitation Crab Sticks with Real Snow Crab (Chionoecetes opilio) Leg Meat Based on Physicochemical and Sensory Characteristics.

Recently, many manufacturers have been developing or producing imitation crab sticks (ICSs) that are highly similar to real snow crab leg meat (RC). This study evaluated the similarities between commercial ICSs and RC based on the analysis of physicochemical and sensory properties. Normal ICS (NS) and premium ICSs either with real crab leg meat (PS-RC) or without it (PS) were compared with RC. The sensory evaluation results showed that PS and NS had the highest and lowest levels of similarity to RC, respectively. The carbohydrate contents of ICSs (10–23%) were higher than that of RC (0.5%). Among ICSs, PS showed more similarity with RC than NS and PS-RC in terms of gel strength and texture profiles. PS-RC and PS showed a microstructural pattern that slightly imitated the muscle fiber arrangement of RC. The electric tongue analysis of taste compounds, such as sugars, free amino acids, and nucleotides, showed that the taste profile of ICSs is distinctly different from that of RC. The electronic nose analysis identified 32 volatile compounds, while the principal component analysis using electronic nose data successfully distinguished three clusters: PS-RC and PS, RC, and NS. Our results could provide useful information for the development of ICSs with higher similarity to RC.

Myocardial biopsy of Liwen procedure: representability and etiological diagnostic value of cardiac samples obtained by a novel technique in patients with hypertrophic cardiomyopathy

Objective: To investigate the representability and etiological diagnostic value of myocardium samples obtained from patients with hypertrophic cardiomyopathy (HCM) by transthoracic echocardiography-guided percutaneous intramyocardial septal biopsy (myocardial biopsy of Liwen procedure). Methods: This study was a retrospective case-series analysis. Patients with HCM, who underwent myocardial biopsy of Liwen procedure and radiofrequency ablation in Xijing Hospital, Air Force Military Medical University from July to December 2019, were included. Demographic data (age, sex), echocardiographic data and complications were collected through electronic medical record system. The histological and echocardiographic features, pathological characteristics of the biopsied myocardium of the patients were analyzed. Results: A total of 21 patients (aged (51.2±14.5) years and 13 males (61.9%)) were enrolled. The thickness of ventricular septum was (23.3±4.5)mm and the left ventricular outflow tract gradient was (78.8±42.6)mmHg (1 mmHg=0.133 kPa). Eight patients (38.1%) were complicated with hypertension, 1 patient (4.8%) had diabetes, and 2 patients (9.5%) had atrial fibrillation. Hematoxylin-eosin staining of myocardial samples of HCM patients before radiofrequency ablation evidenced myocytes hypertrophy, myocytes disarray, nuclear hyperchromatism, hypertrophy, atypia, coronary microvessel abnormalities, adipocyte infiltration, inflammatory cell infiltration, cytoplasmic vacuoles, lipofuscin deposition. Interstitial fibrosis and replacement fibrosis were detected in Masson stained biopsy samples. Hematoxylin-eosin staining of myocardial samples of HCM patients after radiofrequency ablation showed significantly reduced myocytes, cracked nuclear in myocytes, coagulative necrosis, border disappearance and nuclear fragmentation. Quantitative analysis of myocardial specimens of HCM patients before radiofrequency ablation showed that there were 9 cases (42.9%) with mild myocardial hypertrophy and 12 cases (57.1%) with severe myocardial hypertrophy. Mild, moderate and severe fibrosis were 5 (23.8%), 9 (42.9%) and 7 (33.3%), respectively. Six cases (28.6%) had myocytes disarray. There were 11 cases (52.4%) of coronary microvessel abnormalities, 4 cases (19.0%) of adipocyte infiltration, 2 cases (9.5%) of inflammatory cell infiltration,6 cases (28.5%) of cytoplasmic vacuole, 16 cases (76.2%) of lipofuscin deposition. The diameter of cardiac myocytes was (25.2±2.8)μm, and the percentage of collagen fiber area was 5.2%(3.0%, 14.6%). One patient had severe replacement fibrosis in the myocardium, with a fibrotic area of 67.0%. The rest of the patients had interstitial fibrosis. The myocardial specimens of 13 patients were examined by transmission electron microscopy. All showed increased myofibrils, and 9 cases had disorder of myofibrils. All patients had irregular shape of myocardial nucleus, partial depression, mild mitochondrial swelling, fracture and reduction of mitochondrial crest, and local aggregation of myofibrillary interfascicles. One patient had hypertrophy of cardiomyocytes, but the arrangement of muscle fibers was roughly normal. There were vacuoles in the cytoplasm, and Periodic acid-Schiff staining was positive. Transmission electron microscopy showed large range of glycogen deposition in the cytoplasm, with occasional double membrane surround, which was highly indicative of glycogen storage disease. No deposition of glycolipid substance in lysozyme was observed under transmission electron microscope in all myocardial specimens, which could basically eliminate Fabry disease. No apple green substance was found under polarized light after Congo red staining, which could basically exclude cardiac amyloidosis. Conclusion: Myocardium biopsied samples obtained by Liwen procedure of HCM patients are representative and helpful for the etiological diagnosis of HCM.

Electrical cross-sectional imaging of human motor units in vivo

ObjectivesIn many neuromuscular diseases, weakness results from a disruption in muscle fibres' arrangement within a motor unit. Limitations in current techniques mean that the spatial distribution of fibres in human motor units remains unknown. MethodsA flexible multi-channel electrode was developed and bonded to a clinical electromyography (EMG) needle. Muscle fibre action potentials were localised using a novel deconvolution method. This was tested using simulated data, and in recordings collected from the tibialis anterior muscle of healthy subjects. ResultsSimulated data indicated good localisation reliability across all sections of the electrode except the end sections. A corrected fibre density was estimated up to 1.4 fibres/mm2. Across five recordings from three individuals, between 4 and 14 motor units were detected. Between 1 and 20 muscle fibres were localised per motor unit within the electrode detection area, with up to 220 muscle fibres localised per recording, with overlapping motor unit territories. ConclusionsWe provide the first direct evidence that human motor units spatially overlap, as well as data related to the spatial arrangement of muscle fibres within a motor unit. SignificanceAs well as providing insights into normal human motor physiology, this technology could lead to faster and more accurate diagnosis in patients with neuromuscular diseases.

Production of fermented spicy rabbit meat using Lactobacillus paracasei.

Lactobacillus paracasei was used to produce fermented spicy rabbit meat. A series of indexes were determined, including pH value, free amino acid content, true protein content, texture, microstructure and the volatile compounds of fermented spicy rabbit meat and unfermented spicy rabbit meat. The results showed that Lactobacillus paracasei could reduce the pH value of spicy rabbit meat (from 6.85 to 4.65), could degrade the proteins of spicy rabbit meat, could increase the content of free amino acids (from 205.1mg/100g to 505.6mg/100g), and could improve its textural properties and organoleptic quality of the spicy rabbit meat. The microstructure of the fermented spicy rabbit meat and unfermented spicy rabbit meat was observed by scanning electron microscope. The results showed that the microstructure of the fermented spicy rabbit meat changed obviously, the arrangement of muscle fibers was loose or even seriously broken, and many small pieces were formed, which indicated that the fermentation could improve the tenderness of the rabbit meat. The kinds of volatile flavor compounds after fermentation were increased from 14 to 40 as estimated by solid phase microextraction and GC-MS. Therefore, utilization of microbial fermentation technology can improve the quality, texture, tenderness and flavor of spicy rabbit meat, and enhance the digestion and absorption capacity.