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Rabatseta TP, Fourie P, Nkosi BD, Malebana IMM. Effect of dietary inclusion of Pennisetum purpureum (Napier) grass on growth performance, rumen fermentation and meat quality of feedlot sussex red steers. Trop Anim Health Prod 2024; 56:133. [PMID: 38642221 PMCID: PMC11032278 DOI: 10.1007/s11250-024-03959-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 03/22/2024] [Indexed: 04/22/2024]
Abstract
The aim of this study was to evaluate the growth performance, fermentation indices and meat quality of Sussex steers fed totally mixed rations that composed of graded inclusion levels of Napier grass (NP). Three experimental diets designated as diet 1 (0.0 g kg-1 NP: Control), diet 2 (300 g kg-1 NP grass) and diet 3 (600 g kg-1 NP) were formulated. Twenty-four male steers aged 8 months with an average body weight of 185.0 ± 30 kg were used. In a completely randomized design, the animals were allocated to the diets and fed for 120 days. Dietary NP inclusion reduced (P < 0.05) the animals' average daily gain and increased the feed efficiency. The steers' daily feed intake and final body weight decreased (P < 0.05) with a 600 g kg-1 inclusion level. The fermentation indices were not affected (P > 0.05) by the inclusion. While the inclusion reduced (P < 0.05) warm muscle temperature, it had no effect (P > 0.05) on carcass dressing percentage, warm and cold initial and ultimate pH. However, 600 g kg-1 inclusion level reduced (P > 0.05) warm and cold carcass weights. Meat physical attributes, moisture characteristics and tenderness were not affected (P > 0.05) by dietary treatments, except for the 7-days aged meat thaw loss, which increased at 600 g kg-1 inclusion level. Inclusion of 300 g kg-1 increased meat protein and fat, but dry and organic matter contents decreased with increasing inclusion levels. Dietary inclusion of NP grass up to 300 g kg-1 in steers' diets improved feed intake, carcass traits and yielded meat high in protein and fat.
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Affiliation(s)
- T P Rabatseta
- Agricultural Research Council-Animal Production, Irene Campus, Private Bag X2 - Irene 0062, Pretoria, South Africa
- Central University of Technology, Free State Private Bag X20539, Bloemfontein, 9300, South Africa
| | - P Fourie
- Central University of Technology, Free State Private Bag X20539, Bloemfontein, 9300, South Africa
| | - B D Nkosi
- Agricultural Research Council-Animal Production, Irene Campus, Private Bag X2 - Irene 0062, Pretoria, South Africa
| | - I M M Malebana
- Agricultural Research Council-Animal Production, Irene Campus, Private Bag X2 - Irene 0062, Pretoria, South Africa.
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2
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Lookin O, Boulali N, Cazorla O, de Tombe P. Impact of stretch on sarcomere length variability in isolated fully relaxed rat cardiac myocytes. Pflugers Arch 2023; 475:1203-1210. [PMID: 37603101 DOI: 10.1007/s00424-023-02848-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/24/2023] [Accepted: 08/05/2023] [Indexed: 08/22/2023]
Abstract
The contractility of cardiac muscle is greatly affected by preload via the Frank-Starling mechanism (FSM). It is based on preload-dependent activation of sarcomeres-the elementary contractile units in muscle cells. Recent findings show a natural variability in sarcomere length (SL) in resting cardiomyocytes that, moreover, is altered in an actively contracting myocyte. SL variability may contribute to the FSM, but it remains unresolved whether the change in the SL variability is regulated by activation process per se or simply by changes in cell stretch, i.e., average SL. To separate the roles of activation and SL, we characterized SL variability in isolated, fully relaxed rat ventricular cardiomyocytes (n = 12) subjected to a longitudinal stretch with the carbon fiber (CF) technique. Each cell was tested in three states: without CF attachment (control, no preload), with CF attachment without stretch, and with CF attachment and ~ 10% stretch of initial SL. The cells were imaged by transmitted light microscopy to retrieve and analyze individual SL and SL variability off-line by multiple quantitative measures such as coefficient of variation or median absolute deviation. We found that CF attachment without stretch did not affect the extent of SL variability nor average SL. In stretched myocytes, the averaged SL significantly increased, while the SL variability remained unchanged. This result clearly indicates that the non-uniformity of individual SL is not sensitive to the average SL itself in fully relaxed myocytes. We conclude that SL variability per se does not contribute to the FSM in the heart.
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Affiliation(s)
| | - Najlae Boulali
- Laboratoire "Physiologie Et Médecine Expérimentale du Coeur Et Des Muscles," Phymedexp, INSERM, CNRS, Montpellier University, CHU Arnaud de Villeneuve, 34295, Montpellier, France
| | - Olivier Cazorla
- Laboratoire "Physiologie Et Médecine Expérimentale du Coeur Et Des Muscles," Phymedexp, INSERM, CNRS, Montpellier University, CHU Arnaud de Villeneuve, 34295, Montpellier, France
| | - Pieter de Tombe
- Laboratoire "Physiologie Et Médecine Expérimentale du Coeur Et Des Muscles," Phymedexp, INSERM, CNRS, Montpellier University, CHU Arnaud de Villeneuve, 34295, Montpellier, France.
- Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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Walter F, Seydewitz R, Mitterbach P, Siebert T, Böl M. On a three-dimensional model for the description of the passive characteristics of skeletal muscle tissue. Biomech Model Mechanobiol 2023; 22:1499-1514. [PMID: 36550242 PMCID: PMC10511390 DOI: 10.1007/s10237-022-01664-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022]
Abstract
In this work, a three-dimensional model was developed to describe the passive mechanical behaviour of anisotropic skeletal muscle tissue. To validate the model, orientation-dependent axial ([Formula: see text], [Formula: see text], [Formula: see text]) and semi-confined compression experiments (mode I, II, III) were performed on soleus muscle tissue from rabbits. In the latter experiments, specimen deformation is prescribed in the loading direction and prevented in an additional spatial direction, fibre compression at [Formula: see text] (mode I), fibre elongation at [Formula: see text] (mode II) and a neutral state of the fibres at [Formula: see text] where their length is kept constant (mode III). Overall, the model can adequately describe the mechanical behaviour with a relatively small number of model parameters. The stiffest tissue response during orientation-dependent axial compression ([Formula: see text] kPa) occurs when the fibres are oriented perpendicular to the loading direction ([Formula: see text]) and are thus stretched during loading. Semi-confined compression experiments yielded the stiffest tissue ([Formula: see text] kPa) in mode II when the muscle fibres are stretched. The extensive data set collected in this study allows to study the different error measures depending on the deformation state or the combination of deformation states.
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Affiliation(s)
- Fabian Walter
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, D-38106, Braunschweig, Germany
| | - Robert Seydewitz
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, D-38106, Braunschweig, Germany
| | - Philipp Mitterbach
- Mechanical Engineering, Eindhoven University of Technology, NLD-5612, Eindhoven, The Netherlands
| | - Tobias Siebert
- Institute of Sport and Motion Science, University of Stuttgart, D-70569, Stuttgart, Germany
| | - Markus Böl
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, D-38106, Braunschweig, Germany.
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Lookin O, Boulali N, Cazorla O, Tombe P. Impact of stretch on sarcomere length variability in isolated fully relaxed rat cardiac myocytes. RESEARCH SQUARE 2023:rs.3.rs-3043911. [PMID: 37398289 PMCID: PMC10312908 DOI: 10.21203/rs.3.rs-3043911/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The contractility of cardiac muscle is greatly affected by preload via the Frank-Starling Mechanism (FSM). It is based on the preload-dependent activation of sarcomeres - the elementary contractile units in muscle cells. Recent findings show a natural variability in sarcomere length (SL) in resting cardiomyocytes that, moreover, is altered in an actively contracting myocyte. SL variability may contribute to the FSM but it remains unresolved whether the change in the SL variability is regulated by activation process per se or simply by changes in cell stretch, i.e. average SL. To separate the roles of activation and SL, we characterized SL variability in isolated fully relaxed rat ventricular cardiomyocytes ( n = 12) subjected to a longitudinal stretch with the carbon fiber (CF) technique. Each cell was tested in three states: without CF attachment (control, no preload), with CF attachment without stretch, and with CF attachment and ~ 10% stretch of initial SL. The cells were imaged by transmitted light microscopy to retrieve and analyze individual SL and SL variability off-line by multiple quantitative measures like coefficient of variation or median absolute deviation. We found that CF attachment without stretch did not affect the extent of SL variability and averaged SL. In stretched myocytes, the averaged SL significantly increased while the SL variability remained unchanged. This result clearly indicates that the non-uniformity of individual SL is not sensitive to the average SL itself in fully relaxed myocytes. We conclude that SL variability per se does not contribute to the FSM in the heart.
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Affiliation(s)
| | - Najlae Boulali
- Université de Montpellier, INSERM, CNRS, CHU Arnaud de Villeneuve
| | - Olivier Cazorla
- Université de Montpellier, INSERM, CNRS, CHU Arnaud de Villeneuve
| | - Pieter Tombe
- Université de Montpellier, INSERM, CNRS, CHU Arnaud de Villeneuve
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Lookin O, de Tombe P, Boulali N, Gergely C, Cloitre T, Cazorla O. Cardiomyocyte sarcomere length variability: Membrane fluorescence versus second harmonic generation myosin imaging. J Gen Physiol 2023; 155:213827. [PMID: 36695814 PMCID: PMC9930136 DOI: 10.1085/jgp.202213289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/07/2022] [Accepted: 01/10/2023] [Indexed: 01/26/2023] Open
Abstract
Sarcomere length (SL) and its variation along the myofibril strongly regulate integrated coordinated myocyte contraction. It is therefore important to obtain individual SL properties. Optical imaging by confocal fluorescence (for example, using ANEPPS) or transmitted light microscopy is often used for this purpose. However, this allows for the visualization of structures related to Z-disks only. In contrast, second-harmonic generation (SHG) microscopy visualizes A-band sarcomeric structures directly. Here, we compared averaged SL and its variability in isolated relaxed rat cardiomyocytes by imaging with ANEPPS and SHG. We found that SL variability, evaluated by several absolute and relative measures, is two times smaller using SHG vs. ANEPPS, while both optical methods give the same average (median) SL. We conclude that optical methods with similar optical spatial resolution provide valid estimations of average SL, but the use of SHG microscopy for visualization of sarcomeric A-bands may be the "gold standard" for evaluation of SL variability due to the absence of optical interference between the sarcomere center and non-sarcomeric structures. This contrasts with sarcomere edges where t-tubules may not consistently colocalize to Z-disks. The use of SHG microscopy instead of fluorescent imaging can be a prospective tool to map sarcomere variability both in vitro and in vivo conditions and to reveal its role in the functional behavior of living myocardium.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology , Ural Branch of Russian Academy of Sciences , Yekaterinburg, Russia
| | - Pieter de Tombe
- Laboratory "Physiologie et Médecine Expérimentale du Coeur et des Muscles", Phymedexp, INSERM, CNRS, Montpellier University , Montpellier, France.,Physiology and Biophysics, University of Illinois at Chicago , Chicago, IL, USA
| | - Najlae Boulali
- Laboratory "Physiologie et Médecine Expérimentale du Coeur et des Muscles", Phymedexp, INSERM, CNRS, Montpellier University , Montpellier, France
| | - Csilla Gergely
- L2C, University of Montpellier , CNRS , Montpellier, France
| | | | - Olivier Cazorla
- Laboratory "Physiologie et Médecine Expérimentale du Coeur et des Muscles", Phymedexp, INSERM, CNRS, Montpellier University , Montpellier, France
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Contini M, Altman D, Cornachione A, Rassier DE, Bagni MA. An increase in force after stretch of diaphragm fibers and myofibrils is accompanied by an increase in sarcomere length non-uniformities and Ca 2+ sensitivity. Am J Physiol Cell Physiol 2022; 323:C14-C28. [PMID: 35613356 DOI: 10.1152/ajpcell.00394.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When muscle fibers from limb muscles are stretched while activated, the force increases to a steady-state level that is higher than that produced during isometric contractions at a corresponding sarcomere length, a phenomenon known as residual force enhancement (RFE). The mechanisms responsible for the RFE are an increased stiffness of titin molecules which may lead to an increased Ca2+ sensitivity of the contractile apparatus,and the development of sarcomere length non-uniformities. RFE is not observed in cardiac muscles, which makes this phenomenon specific to certain preparations. The aim of this study was to investigate if the RFE is present in the diaphragm, and its potential association with an increased Ca2+ sensitivity and the development of sarcomere length non-uniformities. We used two preparations: single intact fibers and myofibrils isolated from the diaphragm from mice. We investigated RFE in a variety of lengths across the force-length relationship. RFE was observed in both preparations at all lengths investigated, and was larger with increasing magnitudes of stretch. RFE was accompanied by an increased Ca2+ sensitivity as shown by a change in the force-pCa2+-curve, and increased sarcomere length non-uniformities. Therefore, RFE is a phenomenon commonly observed in skeletal muscles, with mechanisms that are similar across preparations.
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Affiliation(s)
- Massimo Contini
- Department of Experimental and Clinical Medicine, University of Florence, Italy
| | - David Altman
- Department of Physics, Willamette University, Salem, OR, United States
| | - Anabelle Cornachione
- Department of Physiological Sciences, Federal University of São Carlos, São Paulo, Brazil
| | | | - Maria Angela Bagni
- Department of Experimental and Clinical Medicine, University of Florence, Italy
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Jakobsen JR, Krogsgaard MR. The Myotendinous Junction-A Vulnerable Companion in Sports. A Narrative Review. Front Physiol 2021; 12:635561. [PMID: 33841171 PMCID: PMC8032995 DOI: 10.3389/fphys.2021.635561] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/15/2021] [Indexed: 01/17/2023] Open
Abstract
The incidence of strain injuries continues to be high in many popular sports, especially hamstring strain injuries in football, despite a documented important effect of eccentric exercise to prevent strains. Studies investigating the anatomical properties of these injuries in humans are sparse. The majority of strains are seen at the interface between muscle fibers and tendon: the myotendinous junction (MTJ). It has a unique morphology with a highly folded muscle membrane filled with invaginations of collagen fibrils from the tendon, establishing an increased area of force transmission between muscle and tendon. There is a very high rate of remodeling of the muscle cells approaching the MTJ, but little is known about how the tissue adapts to exercise and which structural changes heavy eccentric exercise may introduce. This review summarizes the current knowledge about the anatomy, composition and adaptability of the MTJ, and discusses reasons why strain injuries can be prevented by eccentric exercise.
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Affiliation(s)
- Jens Rithamer Jakobsen
- Section of Sports Traumatology, M51, A Part of IOC Research Center, Bispebjerg and Frederiksberg Hospital, Copenhagen University Hospital, Copenhagen, Denmark
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Haeger R, de Souza Leite F, Rassier DE. Sarcomere length non-uniformities dictate force production along the descending limb of the force-length relation. Proc Biol Sci 2020; 287:20202133. [PMID: 33109011 DOI: 10.1098/rspb.2020.2133] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The force-length relation is one of the most defining features of muscle contraction, and yet a topic of debate in the literature. The sliding filament theory predicts that the force produced by muscle fibres is proportional to the degree of overlap between myosin and actin filaments, producing a linear descending limb of the active force-length relation. However, several studies have shown forces that are larger than predicted, especially at long sarcomere lengths (SLs). Studies have been conducted with muscle fibres, preparations containing thousands of sarcomeres that make measurements of individual SL challenging. The aim of this study was to evaluate force production and sarcomere dynamics in isolated myofibrils and single sarcomeres from the rabbit psoas muscle to enhance our understanding of the theoretically predicted force-length relation. Contractions at varying SLs along the plateau (SL = 2.25-2.39 µm) and the descending limb (SL > 2.39 µm) of the force-length relation were induced in sarcomeres and myofibrils, and different modes of force measurements were used. Our results show that when forces are measured in single sarcomeres, the experimental force-length relation follows theoretical predictions. When forces are measured in myofibrils with large SL dispersions, there is an extension of the plateau and forces elevated above the predicted levels along the descending limb. We also found an increase in SL non-uniformity and slowed rates of force production at long lengths in myofibrils but not in single sarcomere preparations. We conclude that the deviation of the descending limb of the force-length relation is correlated with the degree of SL non-uniformity and slowed force development.
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Affiliation(s)
- Ricarda Haeger
- Kinesiology and Physical Education, McGill University, Montreal, QC, Canada
| | | | - Dilson E Rassier
- Kinesiology and Physical Education, McGill University, Montreal, QC, Canada
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