Search

The article investigated the dependence of the histological structure of m. Longissimus thoracis muscle in immunocastrated pigs vaccinated with the “Improvak” vaccine from the company “Zoetis”, USA, and in non-castrated pigs fattened under the conditions of industrial pork production and slaughtered at different live weights. For the study, two experimental groups of 220 gilts each were formed, derived from Irish Landrace and Irish Yorkshire sows and inseminated with semen from boars of the MakGro synthetic line. At the age of 72 days, with an average live weight of 26 kg, they were brought to a fattening farm where the piglets of the research group were vaccinated on the 112th day of life with the vaccine “Improvak” from the company “Zoetis”, USA, in a quantity of 2 ml. They were re-vaccinated on the 148th day of life with the same vaccine and in the same quantity. The pigs in the control group were not castrated. It was found that in m. Longissimus thoracis muscle of immunocastrated pigs using the “Improvak” vaccine, the diameter of the muscle fibres decreased by 15 micrometres and the fibres absorbed more sarcoplasm, which, against the background of a 14 % increase in the content of parenchymal components, indicates an increase in the juiciness and tenderness of the meat. It has been shown that the muscle fibres of the longissimus thoracis no longer grow as a result of the immunocastration of pigs, but take on useful properties, i.e. become hydrated and fat. It was found that pre-slaughter weight had no significant effect on the histological parameters of the longest back muscle of the pigs studied. [ABSTRACT FROM AUTHOR]

The extracellular matrix (ECM) has an important role in the development and maintenance of skeletal muscle, and several muscle diseases are associated with the dysfunction of ECM elements. MAMDC2 is a putative ECM protein and its role in cell proliferation has been investigated in certain cancer types. However, its participation in skeletal muscle physiology has not been previously studied. We describe 17 individuals with an autosomal dominant muscular dystrophy belonging to two unrelated families in which different heterozygous truncating variants in the last exon of MAMDC2 co-segregate correctly with the disease. The radiological aspect of muscle involvement resembles that of COL6 myopathies with fat replacement at the peripheral rim of vastii muscles. In this cohort, a subfascial and peri-tendinous pattern is observed in upper and lower limb muscles. Here we show that MAMDC2 is expressed in adult skeletal muscle and differentiating muscle cells, where it appears to localize to the sarcoplasm and myonuclei. In addition, we show it is secreted by myoblasts and differentiating myotubes into to the extracellular compartment. The last exon encodes a disordered region with a polar residue compositional bias loss of which likely induces a toxic effect of the mutant protein. The precise mechanisms by which the altered MAMDC2 proteins cause disease remains to be determined. MAMDC2 is a skeletal muscle disease-associated protein. Its role in muscle development and ECM-muscle communication remains to be fully elucidated. Screening of the last exon of MAMDC2 should be considered in patients presenting with autosomal dominant muscular dystrophy, particularly in those with a subfascial radiological pattern of muscle involvement. [ABSTRACT FROM AUTHOR]

The main purpose of the experiment carried out was to study the effects of immunological castration of gilts on the histological indicators of the muscle tissue of m. Longissimus thoracis muscle tissue compared to non-castrated animals. For the study, 440 pigs were collected, which were initially divided into two groups of 220 animals each, one of which was immunologically castrated and the other not castrated. At the end of fattening, the group of immunocastrated and non-castrated gilts was divided by weight into groups of 110 and 130 kg, resulting in four groups: noncastrated gilts with a live weight of 110 kg, non-castrated gilts with a live weight of 130 kg, immunocastrated gilts with a live weight of 110 kg and immunocastrated gilts of 130 kg. After slaughter, histological sections of the longest dorsal muscle were taken and light-optical and morphometric examinations, luminescence microscopy with microphotography of m. Longissimus thoracis muscle were carried out. As a result of the experiments, it was found that as a result of immunological castration of gilts with the Improvak vaccine, the muscle fibre diameter decreased by 15 μm and the muscle fibres absorbed a larger amount of sarcoplasm, which, against the background of an increase in the content of the parenchymal component (by 14%), indicates an increase in the juiciness and tenderness of the meat. [ABSTRACT FROM AUTHOR]

The issue of rational nutrition of children is still extremely relevant and an effective factor in ensuring the preservation of the life and health of children. Pathological conditions associated with intolerance to certain components of food are increasingly common. Biologically complete products play an important role in the organization of rational nutrition of children, which can be created only in industrial production conditions. When assessing the chemical composition of experimental goat meat samples (Zaanenskaya, Alpine, Nubian), no abnormal deviations were detected, and all indicators were in the generally accepted contents of this type of animal muscle tissue. The mineral composition showed that goat meat is rich in such elements as potassium - 1693.22 - 4125.83 mg/kg; sodium - 852.27 - 1518 mg/kg, magnesium - 125.33 - 295.8 mg/kg; calcium - 79.27 - 160.79 mg/kg, iron 11.42-87.52 mg/kg. The vitamin composition of goat meat showed that the content of pantothenic acid (B5) was 0.53 - 0.62 mg / 100g, pyridoxine (B6) 0.52 - 0.64 mg/100g tocopherol 0.27 - 0.33 mg/100g. The mass fraction of goat meat proteins was 2.1 ±0.3 - 2.4 ±0.4%. The study of the dynamics of changes in the composition of protein fractions based on the results of comparative studies of the ratio of sarcoplasmic proteins showed the content of water-soluble (1.75 - 4.06%), salt-soluble (1.75 - 2.44%), alkali-soluble (11.15 - 15.10%) proteins. The salt-soluble fraction reflects the total changes in the state of protein fractions, the solubility of which was not the same for the rocks under consideration (the highest concentration was determined in the Nubian rock). [ABSTRACT FROM AUTHOR]

We sought to determine if manipulating resistance training (RT) variables differentially altered the expression of select sarcoplasmic and myofibril proteins as well as myofibrillar spacing in myofibers. Resistance-trained men (n = 20; 26 ± 3 years old) trained for 8 weeks where a randomized leg performed either a standard (CON) or variable RT protocol (VAR: manipulation of load, volume, muscle action, and rest intervals at each RT session). A pre-training (PRE) vastus lateralis biopsy was obtained from a randomized single leg, and biopsies were obtained from both legs 96 h following the last training bout. The sarcoplasmic protein pool was assayed for proteins involved in energy metabolism, and the myofibril protein pool was assayed for relative myosin heavy chain (MHC) and actin protein abundances. Sections were also histologically analyzed to obtain myofibril spacing characteristics. VAR resulted in ~12% greater volume load (VL) compared to CON (p < 0.001). The mean fiber cross-sectional area increased following both RT protocols [CON: 14.6% (775.5 μm2), p = 0.006; VAR: 13.9% (743.2 μm2), p = 0.01 vs. PRE for both], but without significant differences between protocols (p = 0.79). Neither RT protocol affected a majority of assayed proteins related to energy metabolism, but both training protocols increased hexokinase 2 protein levels and decreased a mitochondrial beta-oxidation marker (VLCAD protein; p < 0.05). Citrate synthase activity levels increased with CON RT (p < 0.05), but not VAR RT. The relative abundance of MHC (summed isoforms) decreased with both training protocols (p < 0.05). However, the relative abundance of actin protein (summed isoforms) decreased with VAR only (13.5 and 9.0%, respectively; p < 0.05). A decrease in percent area occupied by myofibrils was observed from PRE to VAR (−4.87%; p = 0.048), but not for the CON (4.53%; p = 0.979). In contrast, there was an increase in percent area occupied by non-contractile space from PRE to VAR (10.14%; p = 0.048), but not PRE to CON (0.72%; p = 0.979). In conclusion, while both RT protocols increased muscle fiber hypertrophy, a higher volume-load where RT variables were frequently manipulated increased non-contractile spacing in resistance-trained individuals. [ABSTRACT FROM AUTHOR]

Consisting of 25 to 30% of protein in carp, water‐soluble sarcoplasmic proteins lost in wash water, have been recovered and freeze‐dried into a protein‐rich powder. Study objectives were to evaluate protein quality and safety of a silver carp sarcoplasm derived protein powder (CSP) compared to commercial protein supplements, casein, and whey. In vivo protein quality assessment of CSP showed a lower (P < 0.05) protein digestibility corrected amino acid score compared to the commercial protein sources. Despite greater (P < 0.05) fecal amino acid excretion in casein‐fed rats, there were no significant differences in liver and muscle amino acid profiles. All low (10% kcal) protein diets supported growth with the normal range. However, whey protein supplementation resulted in greater (P < 0.05) adiposity. CSP, casein, or whey‐fed rats showed no differences in major organ weights, renal damage biomarkers, or bone indices. Collectively, results indicated CSP was safe with protein quality comparable to casein. Practical Application: As much as 40 percent of protein in fish can be lost due to sarcoplasmic protein solubilization in processing wash water. Silver carp sarcoplasm protein powder may have similar commercial potential as a sustainable and nutritious alternative to whey and casein proteins. This project aimed to verify the protein quality and safety of this economical protein source. [ABSTRACT FROM AUTHOR]

Skeletal muscle fibers are multinucleated cells that contain mostly myofibrils suspended in an aqueous media termed the sarcoplasm. Select evidence suggests sarcoplasmic hypertrophy, or a disproportionate expansion of the sarcoplasm relative to myofibril protein accretion, coincides with muscle fiber or tissue growth during resistance training. There is also evidence to support other modes of hypertrophy occur during periods of resistance training including a proportional accretion of myofibril protein with fiber or tissue growth (i.e., conventional hypertrophy), or myofibril protein accretion preceding fiber or tissue growth (i.e., myofibril packing). In this review, we discuss methods that have been used to investigate these modes of hypertrophy. Particular attention is given to sarcoplasmic hypertrophy throughout. Thus, descriptions depicting this process as well as the broader implications of this phenomenon will be posited. Finally, we propose future human and rodent research that can further our understanding in this area of muscle physiology. [ABSTRACT FROM AUTHOR]

Copyright of Polish Journal of Thoracic & Cardiovascular Surgery / Kardiochirurgia i Torakochirurgia Polska is the property of Termedia Publishing House and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Protein phosphorylation is a key modulator in glycolysis metabolism and regulates the activity of glycometabolic enzymes. The phosphorylation levels of sarcoplasmic proteins were investigated in relationship to the glycolysis rate in postmortem ovine muscle in the present study. The global phosphorylation levels of sarcoplasmic proteins increased early postmortem and then decreased afterwards in postmortem ovine muscle. Protein bands of different phosphorylation levels were identified as glycometabolism‐related enzymes. The phosphorylation levels of Glycogen phosphorylase and Pyruvate kinase maybe one possible reason for the different glycolytic rates at 0.5 h postmortem. The glycolytic rate attributes were negatively correlated with four bands which were probably phosphofructokinase, enolase and adenylate kinase isoenzyme. In summary, the phosphorylation of sarcoplasmic proteins is related to muscle pH decline early postmortem, influencing the meat rigour mortis and quality development. Quantification of global phosphorylation levels of sarcoplasmic proteins. [ABSTRACT FROM AUTHOR]

A comparative analysis of the spectral characteristics of the surface of muscular tissue of animal origin (pork) and its main components has been performed by the methods of diffuse reflection electronic spectroscopy (DRES) and frustrated total internal reflection IR spectroscopy. The experiments have shown that the application of the DRES method makes it possible to detect more pronounced changes in the surface optical characteristics of muscular tissue and obtain electronic spectra containing information about the component composition of its main parts under successive extraction of sarcoplasmic materials, myofibrillar proteins of the actomyosin complex, and stroma mucopolysaccharides. [ABSTRACT FROM AUTHOR]

Two new species of Microsporidia were recognized in skeletal muscle of freshwater fishes from Finland. Myosporidium spraguei n. sp. from pike-perch Sander lucioperca occurred as mature spores within sporophorous vesicles (SPVs) within a xenoma. The ovoid spores were 3.8 μm long and 2.4 μm wide, based on transmission electron micrographs (TEM). The exospore and endospore were equally thick, the nucleus was monokaryotic and the polar filament was isofilar with 12 coils in a single rank, entirely adjacent to the prominent posterior vacuole. Small subunit (SSU) rDNA sequence confirmed the presence of M. spraguei n. sp. in burbot Lota lota. The second species, Microsporidium luciopercae n. sp., also from pike-perch, occurred within SPVs that occupied only a fraction of the volume of the otherwise intact myocyte; no xenoma was produced. Myocyte degeneration and necrosis occurred as mature spores dispersed into direct contact with the sarcoplasm. The ovoid spores were 4.6 μm long and 2.8 μm wide (based on TEM); they were monokaryotic and the polar filament was isofilar with 25 coils in a single rank in the posterior of the spore. The exospore was relatively thin with an irregular profile. Neither infection elicited an inflammatory response, although degenerate spores were observed within host cells, suggesting phagocytosis. Phylogenetic analysis of SSU sequences placed both organisms on distinct clades within the Marinosporidia. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Science (John Wiley & Sons, Inc.) is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study uses scanning and transmission electron microscopical observations to examine the haptoral features of the hexabothriid polyopisthocotylean monogenean Rajonchocotyle emarginata from the gills of the elasmobranch Amblyraja radiata. The haptor possesses six equal, pedunculate suckers, each armed with a large, curved, hooked sclerite, and an appendix bearing two small, terminal suckers and a pair of minute hamuli. The outer side of the distal region of the hooked sclerite forms a large bulge along the antero-lateral side of each sucker and the proximal region forms a small bulge on the opposite postero-lateral side; part of the large bulge, which covers the small sclerite hook, surmounts the sucker rim. The sucker sclerite is situated outside the main sucker muscle complex of the sucker wall and is surrounded by its own muscular envelope; close to the sclerite itself, long, tightly packed lamella-like processes of sarcoplasm are present. A muscular sphincter surrounds the distal region of the sclerite shaft. The sclerite consists of three heterogeneous layers, but its hook region is distinguished from the shaft by the presence of an additional homogeneous layer. Hamuli within the appendix consist of three distinct layers loosely surrounded by sarcoplasmic lamellae. The luminal surface of the appendicular suckers is covered with unusual, long, thin, interconnected surface protrusions. In all other regions of the haptor, the tegumental surface is smooth, with numerous shallow pores penetrating the 'terminal web' of the syncytial cytoplasm. Unicellular gland cells are localized close to the base of the appendix, with their ducts, containing non-homogenous secretory bodies, opening onto the anterior haptoral surface. Two types of sense receptors are visible on the haptoral surface. The ultrastructural features of the haptor are discussed in relation to our understanding of their function and the evolutionary relationships of the basal polyopisthocotylean monogenean groups Hexabothriidae and Chimaericolidae. [ABSTRACT FROM AUTHOR]

The sarcoplasmic proteins from hake ( Merluccius merluccius) were subjected to high-pressure treatments (200, 400 and 600 MPa for 6 min at 20 °C). The physicochemical changes and the emulsifying capacity of sarcoplasmic proteins were evaluated. High-pressure processing increased the surface hydrophobicity and the reactive sulfhydryl group content of sarcoplasmic proteins above 200 MPa. Likewise, conformational changes were induced on the secondary structure of sarcoplasmic proteins at 400 MPa. High-pressure denaturation of sarcoplasmic proteins promoted their aggregation. The electrophoretic patterns showed that some sarcoplasmic proteins (78, 73, 63, 58, 37, 32 and 22 kDa) were the most pressure labile. However, the carbonyl content of sarcoplasmic proteins was not affected by high-pressure treatments. The pressure-induced denaturation affected the emulsifying properties of sarcoplasmic proteins, which was dependent on pressure. In contrast to high-pressure levels (400 and 600 MPa), sarcoplasmic proteins treated at 200 MPa produced emulsions with enhanced stability, greater consistency index, and shear-thinning behavior. These results suggested that high-pressure denaturation can affect the functional properties of sarcoplasmic proteins. [ABSTRACT FROM AUTHOR]

The aim of this research was to correlate the postmortem changes of sarcoplasmic proteins with instrumental color and various biochemical parameters relating to color attributes. Two-dimensional electrophoresis was used to investigate sarcoplasmic protein changes in cardiac muscle during refrigerated storage. Eleven differentially abundant protein spots were identified between storage time at day 1 and day 5 ( P < 0.05). The functional category of proteins consisted of metabolic enzymes, binding proteins, chaperone proteins, and antioxidant proteins. These proteins demonstrated positive correlation with a*-value (creatine kinase M-type and malate dehydrogenase), metmyoglobin-reducing activity (aconitate hydratase, creatine kinase, and thioredoxin-dependent peroxide reductase), tissue oxygen consumption rate (creatine kinase and malate dehydrogenase), and mitochondrial respiration control ratio (thioredoxin-dependent peroxide reductase and mitochondrial superoxide dismutase). The protein patterns were likely to have impact on postmortem metabolism, thereby protecting muscle against discoloration. [ABSTRACT FROM AUTHOR]

During early stages of myotomal myogenesis, the myotome of Egyptian cobra ( Naja haje) is composed of homogenous populations of mononucleated primary myotubes. At later developmental phase, primary myotubes are accompanied by closely adhering mononucleated cells. Based on localization and morphology, we assume that mononucleated cells share features with satellite cells involved in muscle growth. An indirect morphological evidence of the fusion of mononucleated cells with myotubes is the presence of numerous vesicles in the subsarcolemmal region of myotubes adjacent to mononucleated cell. As differentiation proceeded, secondary muscle fibres appeared with considerably smaller diameter as compared to primary muscle fibre. Studies on N. haje myotomal myogenesis revealed some unique features of muscle differentiation. TEM analysis showed in the N. haje myotomes two classes of muscle fibres. The first class was characterized by typical for fast muscle fibres regular distribution of myofibrils which fill the whole volume of muscle fibre sarcoplasm. White muscle fibres in studied species were a prominent group of muscles in the myotome. The second class showed tightly paced myofibrils surrounding the centrally located nucleus accompanied by numerous vesicles of different diameter. The sarcoplasm of these cells was characterized by numerous lipid droplets. Based on morphological features, we believe that muscle capable of lipid storage belong to slow muscle fibres and the presence of lipid droplets in the sarcoplasm of these muscles during myogenesis might be a crucial adaptive mechanisms for subsequent hibernation in adults. This phenomenon was, for the first time, described in studies on N. haje myogenesis. [ABSTRACT FROM AUTHOR]

Defective regulation of the alternative pathway of the complement system is believed to contribute to damage of retinal pigment epithelial (RPE) cells in age-related macular degeneration. Thus we investigated the effect of complement activation on the RPE cell membrane by analyzing changes in membrane conductance via patch-clamp techniques and Ca imaging. Exposure of human ARPE-19 cells to complement-sufficient normal human serum (NHS) (25 %) resulted in a biphasic increase in intracellular free Ca ([Ca]); an initial peak followed by sustained Ca increase. C5- or C7-depleted sera did not fully reproduce the signal generated by NHS. The initial peak of the Ca response was reduced by sarcoplasmic Ca-ATPase inhibitor thapsigargin, L-type channel blockers (R)-(+)-BayK8644 and isradipine, transient-receptor-potential (TRP) channel blocker ruthenium-red and ryanodine receptor blocker dantrolene. The sustained phase was carried by Ca1.3 L-type channels via tyrosine-phosphorylation. Changes in [Ca] were accompanied by an abrupt hyperpolarization, resulting from a transient increase in membrane conductance, which was absent under extracellular Ca- or K-free conditions and blocked by (R)-(+)-BayK8644 or paxilline, a maxiK channel inhibitor. Single-channel recordings confirmed the contribution of maxiK channels. Primary porcine RPE cells responded to NHS in a comparable manner. Pre-incubation with NHS reduced HO-induced cell death. In summary, in a concerted manner, C3a, C5a and sC5b-9 increased [Ca] by ryanodine-receptor-dependent activation of L-type channels in addition to maxi-K channels and TRP channels absent from any insertion of a lytic pore. [ABSTRACT FROM AUTHOR]

Introduction: Nemaline myopathy is a rare genetic muscle disorder defined by the presence of nemaline rods in the muscle fibre sarcoplasm. Congenital nemaline myopathy is the most serious form of the disease's spectrum. Case presentation: The affected newborn has no spontaneous movement, fractures at birth and respiratory insufficiency. The present case was a Thai male, floppy at birth with fractures of both humeri and femurs and ventilator-dependent respiration. The patient developed bilateral chylothorax two weeks later and died at the age of 6 weeks. Whole-body postmortem examination with informed consent and genetic analysis of ACTA1 mutation were performed. A skeletal muscle biopsy examined by light and transmission electron microscopy showed the features of nemaline myopathy. ACTA 1 heterozygous missense mutation (c.1127G > C) was identified. Histological examination of both lungs revealed primary pulmonary lymphangiectasia. Conclusion: To the best of our knowledge, congenital nemaline myopathy with primary pulmonary lymphangiectasia causing bilateral chylothrax has never been previously reported. Considering chylothorax as a poor prognostic index and an unusual clinical presentation of severe congenital NM are proposed. [ABSTRACT FROM AUTHOR]

Key points Prolonged Ca2+ transients and Ca2+ waves have been observed in mammalian skeletal muscle upon reducing the normal resting inhibition of the ryanodine receptor (RyR)/Ca2+ release channels of the sarcoplasmic reticulum (SR) by lowering cytoplasmic [Mg2+] ([Mg2+]cyto). The mechanism driving Ca2+ release under these conditions may have pathophysiological implications but is poorly understood., The lowering of [Mg2+]cyto induced a leak of Ca2+ from the SR that triggered a local reduction of the SR Ca2+ buffering power to induce the rise in [Ca2+]SR, an intra-SR Ca2+ transient. Prolonged Ca2+ transients always developed following this event and evolved as propagating Ca2+ waves. No classical hallmarks of cytoplasmic Ca2+ propagation mechanisms were observed in conjunction with these waves., In conjunction with the spread of Ca2+ release, Ca2+ was observed to diffuse through the SR away from the site of the intra-SR Ca2+ transient. Ca2+ release was sustained by the action of SR Ca2+ pumps, presumably to maintain [Ca2+]SR above an inactivation threshold for closure of the RyRs. Inactivation of prolonged Ca2+ release allowed [Ca2+]SR to recover to threshold for activation of further Ca2+ waves, which were always briefer in duration than the initial Ca2+ release transients, consistent with a reduced SR Ca2+ buffering capacity., These observations reveal activation of Ca2+ release in mammalian skeletal muscle by [Ca2+]SR in the absence of the normal resting inhibition of the RyR and changes in voltage. Diffusion of Ca2+ within SR promotes propagation of Ca2+ release., Abstract Skeletal muscle fibres are large and highly elongated cells specialized for producing the force required for posture and movement. The process of controlling the production of force within the muscle, known as excitation-contraction coupling, requires virtually simultaneous release of large amounts of Ca2+ from the sarcoplasmic reticulum (SR) at the level of every sarcomere within the muscle fibre. Here we imaged Ca2+ movements within the SR, tubular (t-) system and in the cytoplasm to observe that the SR of skeletal muscle is a connected network capable of allowing diffusion of Ca2+ within its lumen to promote the propagation of Ca2+ release throughout the fibre under conditions where inhibition of SR ryanodine receptors (RyRs) was reduced. Reduction of cytoplasmic [Mg2+] ([Mg2+]cyto) induced a leak of Ca2+ through RyRs, causing a reduction in SR Ca2+ buffering power argued to be due to a breakdown of SR calsequestrin polymers, leading to a local elevation of [Ca2+]SR. The local rise in [Ca2+]SR, an intra-SR Ca2+ transient, induced a local diffusely rising [Ca2+]cyto. A prolonged Ca2+ wave lasting tens of seconds or more was generated from these events. Ca2+ waves were dependent on the diffusion of Ca2+ within the lumen of the SR and ended as [Ca2+]SR dropped to low levels to inactivate RyRs. Inactivation of RyRs allowed re-accumulation of [Ca2+]SR and the activation of secondary Ca2+ waves in the persistent presence of low [Mg2+]cyto if the threshold [Ca2+]SR for RyR opening could be reached. Secondary Ca2+ waves occurred without an abrupt reduction in SR Ca2+ buffering power. Ca2+ release and wave propagation occurred in the absence of Ca2+-induced Ca2+ release. These observations are consistent with the activation of Ca2+ release through RyRs of lowered cytoplasmic inhibition by [Ca2+]SR or store overload-induced Ca2+ release. Restitution of SR Ca2+ buffering power to its initially high value required imposing normal resting ionic conditions in the cytoplasm, which re-imposed the normal resting inhibition on the RyRs, allowing [Ca2+]SR to return to endogenous levels without activation of store overload-induced Ca2+ release. These results are discussed in the context of how pathophysiological Ca2+ release such as that occurring in malignant hyperthermia can be generated. [ABSTRACT FROM AUTHOR]

This study investigated the effects of high-pressure treatment on the redox states of myoglobin (Mb) species and the associated color stability of porcine during cold storage. Mb was denatured with increasing pressure and temperature. Ferric Mb exhibited more denaturation at the given pressure and temperature conditions as compared to its ferrous analog, part of ferric Mb was reduced back into ferrous form by high-pressure treatment, and the maximum reduction was shown at the pressure level of 150 MPa at 50 °C. Based on the model study, metMb reduction was favorable when the pressure was below 170 MPa, while Mb denaturation was dominant at higher pressures. Pressure treatment of pork resulted in irreversible Mb denaturation, which prevented the restoration of meat color during cold storage, despite the fact that pressure treatment also improved the metMb-reducing activity of pork. Thus, the results of this study demonstrated that pressure-treated pork color was affected by a balance of the redox systems and by the degree of Mb denaturation. In addition, pressurization at around 150-200 MPa was determined to be ideal in terms of improving the color stability of pressurized pork during storage. [ABSTRACT FROM AUTHOR]

Background Drumming muscles of some sound-producing fish are 'champions' of contraction speed, their rate setting the fundamental frequency. In the piranha, contraction of these muscles at 150 Hz drives a sound at the same frequency. Drumming muscles of different not closely related species show evolutionary convergences. Interestingly, some characters of sonic muscles can also be found in the trunk muscles of newly hatched larvae that are able to maintain tail beat frequencies up to 100 Hz. The aim of this work was to study the development of sound production and sonic and epaxial muscles simultaneously in the red bellied piranhas (Pygocentrus nattereri) to seek for possible common characteristics. Results Call, pulse and period durations increased significantly with the fish size, but the call dominant frequencies decreased, and the number of pulses and the call amplitude formed a bell curve. In epaxial muscles, the fibre diameters of younger fish are first positioned in the graphical slope corresponding to sonic muscles, before diverging. The fibre diameter of older fish trunk muscles was bigger, and the area of the myofibrils was larger than in sonic muscles. Moreover, in two of the biggest fish, the sonic muscles were invaded by fat cells and the sonic muscle ultrastructure was similar to the epaxial one. These two fish were also unable to produce any sound, meaning they lost their ability to contract quickly. Conclusions The volume occupied by myofibrils determines the force of contraction, the volume of sarcoplasmic reticulum sets the contraction frequency, and the volume of mitochondria sets the level of sustained performance. The functional outcomes in muscles are all attributable to shifts in the proportions of those structures. A single delay in the development restricts the quantity of myofibrils, maintains a high proportion of space in the sarcoplasm and develops sarcoplasmic reticulum. High-speed sonic muscles could thus be skeletal muscles with delayed development. This hypothesis has the advantage that it could easily explain why high-speed sonic muscles have evolved so many times in different lineages. [ABSTRACT FROM AUTHOR]

Textural properties and changes of myofibrillar and sarcoplasmic proteins ofsalame Felino, a typical Italian dry-cured fermented sausage, were studied during ripening. Hardness, chewiness, and gumminess increased over the ripening period. Adhesiveness showed a gradual but significant decrease after 14 days and further at 28 days of ripening. A remarkable increase of the proteolysis index and a significant decrease of myofibrillar and sarcoplasmic protein solubility were observed. Hardness showed a significant negative correlation with myofibrillar protein solubility. Sarcoplasmic proteins appeared to be more susceptible to degradation. [ABSTRACT FROM PUBLISHER]

The article presents the discussion on exploring preclinical drug discovery focusing on the apparent trafficking defects highlighting the identification of specific protein aggregates in the sarcoplasm of BrS cardiac tissue.

Thermal stability of sarcoplasmic protein and myofibrillar protein extracted from fresh and frozen common carp was comparatively studied. Total sulphydryl content ( SH) in sarcoplasmic protein solution from 5-month frozen carp decreased by 19.43% compared with fresh sample. The SDS- PAGE patterns showed that all the bands of sarcoplasmic protein from frozen-stored samples were almost invisible at 80 °C. Myofibrillar protein from fresh sample exhibited lower turbidity and surface hydrophobicity and higher Ca2+- ATPase activity and SH content than frozen-stored sample when heated from 20 to 80 °C. The Ca2+- ATPase activity from fresh ( M0), 2 ( M2)- and 5 ( M5)-month frozen-stored carp was completely lost at 48, 46 and 46 °C, respectively. When heated to 80 °C, the SH content of myofibrillar solutions in M0, M2 and M5 decreased by 26%, 60% and 70%, respectively. Sarcoplasmic and myofibrillar proteins from frozen carp were more susceptible to aggregate during heating treatment. [ABSTRACT FROM AUTHOR]

Copyright of Gazette of Chemists, Technologists & Environmentalists of Republic of Srpska / Glasnik Hemicara, Tehnologa i Ekologa Republike Srpske is the property of University of Banja Luka, Faculty of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Two gelatin-hydrolyzing proteinases with molecular masses of 85 and 72 kDa in the sarcoplasmic fraction of grass carp muscle were detected using gelatin zymography. The gelatinolytic activity in dark muscle was obviously higher than that in white muscle. Optimum pH and temperature of the two enzymes were around 8.0 and 40C. The proteinase inhibitor leupeptin entirely inhibited GP-I, but E-64 did not inhibit it. Only EDTA completely suppressed GP-II, and Ca2+ is essential for the activity of GP-II. All these facts indicated that GP-I was matrix serine proteinase, and GP-II was matrix metalloproteinase. When grass carp muscle was stored for 15 days at 4C, GP-I and GP-II were detected during the whole stored period. Therefore, the two gelatinolytic proteinases may be proposed to participate in the tenderization of fish muscle during postmortem stage. PRACTICAL APPLICATIONS Gelatinolytic proteinases from grass carp can effectively hydrolyze gelatin. These proteinases may be used to hydrolyze gelatin for peptide that has been added to food products as additive to improve texture. In addition, this study will be significant to learn and comparatively study the properties of gelatinolytic proteinases in fresh fish. Furthermore, this study will surely be beneficial for understanding the mechanism of postmortem tenderization of fish muscle. [ABSTRACT FROM AUTHOR]

Within animal skeletal muscle, focal adhesion kinase (FAK) has been associated with load-dependent molecular and metabolic adaptation including the regulation of insulin sensitivity. This study aimed to generate the first visual images of the localisation of FAK within human skeletal muscle fibres and its associated microvasculature using widefield and confocal immunofluorescence microscopy. Percutaneous muscle biopsies, taken from five lean, active males, were frozen and 5-μm cryosections were incubated with FAK antibodies for visualisation in muscle fibres and the microvasculature. Anti-myosin heavy chain type I was used for fibre-type differentiation. Muscle sections were also incubated with anti-dihydropyridine receptor (DHPR) to investigate co-localisation of FAK with the t-tubules. FITC-conjugated Ulex europaeus Agglutinin I stained the endothelium of the capillaries, whilst anti-smooth muscle actin stained the vascular smooth muscle of arterioles. Fibre-type differences in the intensity of FAK immunofluorescence were determined with image analysis software. In transversely and longitudinally orientated fibres, FAK was localised at the sarcolemmal regions. In longitudinally orientated fibres, FAK staining also showed uniform striations across the fibre and co-staining with DHPR suggests FAK associates with the t-tubules. There was no fibre-type difference in sarcoplasmic FAK content. Within the capillary endothelium and arteriolar smooth muscle, FAK was distributed heterogeneously as clusters. This is the first study to visualise FAK in human skeletal muscle microvasculature and within the (sub)sarcolemmal and t-tubule regions using immunofluorescence microscopy. This technique will be an important tool for investigating the role of FAK in the intracellular signalling of human skeletal muscle and the endothelium of its associated microvasculature. [ABSTRACT FROM AUTHOR]

Recent data indicate that Ca2+ cycling in isolated atrioventricular node (AVN) cells contributes to setting spontaneous rate. The aim of the present study was to extend this observation to the intact AVN in situ, by evaluating the effects of inhibiting sarcoplasmic reticulum Ca2+ uptake with cyclopiazonic acid (CPA) on intact AVN spontaneous activity and its response to isoprenaline. A model of the AVN-paced heart was produced to investigate intact AVN automaticity, by surgical ablation of the sino-atrial node (SAN) in the rabbit Langendorff-perfused heart. Electrograms were recorded from a site close to the AVN (triangle of Koch), an atrial site above the AVN, the left atrium and right ventricle, enabling AVN pacing of the preparation to be confirmed. Before SAN ablation, the heart rate was 166.8 ± 5.4 beats min−1. Ablation of the SAN was clearly indicated by a sudden and significant decrease of heart rate to 108.6 ± 9.6 beats min−1 ( P < 0.01, n = 10). Isoprenaline (100 n m) increased AVN rate to 187.8 ± 12.0 beats min−1 after 1 min of application ( P < 0.01, n = 10). Cyclopiazonic acid (10 and 30 μ m) decreased AVN rate to 81.6 ± 4.8 ( n = 9) and 77.4 ± 6.0 beats min−1 ( n = 7), respectively [ P < 0.05, 10 or 30 μ m CPA versus control ( n = 10)] and also reduced the AVN rate increase in response to isoprenaline from 78.8 ± 10.0 to 46.8 ± 6.8 and 26.7 ± 5.3%, respectively ( P < 0.01). These inhibitory effects of CPA on the intact AVN rate and its response to isoprenaline indicate that Ca2+ cycling is important to the intact AVN spontaneous activity and its acceleration during sympathetic stimulation. [ABSTRACT FROM AUTHOR]

Mice with a knock-in mutation (Y524S) in the type I ryanodine receptor (Ryr1), a mutation analogous to the Y522S mutation that is associated with malignant hyperthermia in humans, die when exposed to short periods of temperature elevation (?37 °C). We show here that treatment with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) prevents this heat-induced sudden death in this mouse model. The protection by AICAR is independent of AMP-activated protein kinase (AMPK) activation and results from a newly identified action of the compound on mutant Ryr1 to reduce Ca2+ leak from the sarcoplasmic reticulum to the sarcoplasm. AICAR thus prevents Ca2+-dependent increases in the amount of both reactive oxygen species (ROS) and reactive nitrogen species (RNS) that act to further increase resting Ca2+ concentrations. If unchecked, the temperature-driven increases in resting Ca2+ concentrations and the amounts of ROS and RNS create an amplifying cycle that ultimately triggers sustained muscle contractions, rhabdomyolysis and death. Although antioxidants are effective in reducing this cycle in vitro, only AICAR prevents heat-induced death in vivo. Our findings suggest that AICAR is probably effective in prophylactic treatment of humans with enhanced susceptibility to exercise- and/or heat-induced sudden death associated with RYR1 mutations. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Hygiene & Experimental Medicine / Postepy Higieny i Medycyny Doswiadczalnej is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Darier's disease (DD, OMIM 124200) is an autosomal dominant inherited genodermatosis characterized by warty papules and plaques in seborrheic areas, and loss of adhesion between suprabasal epidermal keratinocytes (acantholysis) and abnormal keratinisation (dyskeratosis). Till date, more than 150 pathogenic mutations in the ATP2A2 (SERCA2) gene, which encodes the sarcoplasmic/endoplasmic reticulum Ca ATPase isoform 2, have been identified as the genetic basis of DD. Our report of eight DD patients from Austria add seven novel variants (L32P, 149-158del10 each in two different non-consanguineous patients, S72Y, F73S, K460X, 2734delC, T982 M) to the repertoire of ATP2A2 mutations in the DD database which is in line with previous reports that most mutations are related to the 5′- and the 3′-end of the gene. [ABSTRACT FROM AUTHOR]

The goal of the work was a study of the effect of exhaustive weightlifting exercise on prolonged changes in the physiological and biochemical variables characterizing the functional state of skeletal muscles. An exercise accentuated at muscles of the hip surface gave rise to a significant increase of the blood lactate concentration, which indicated that aerobic metabolism was a predominant mechanism of energy supply for muscle contraction. A reduction of the m. rectus femoris EMG amplitude and frequency, a decrease in the tone of tension, and an increase in the tone of relaxation were found immediately after exercise. One day later, the amplitude and the frequency of the EMG signal increased. On day 3, the activity of creatine kinase (CK, a marker of muscle injury) considerably increased, while the amplitude and frequency of EMG decreased. By the ninth day of recovery, all measured variables with the exception of CK were normalized. A significant negative correlation was found between the blood serum's lactate concentration and m. rectus femoris EMG activity at the same time points. Blood serum CK activity and m. rectus femoris EMG and tone parameters were significantly correlated on the third postexercise day. The data demonstrate that exhaustive exercise-induced muscle injury resulted in phasic alterations in the electrical activity and the tone of the muscle apparently related to a decrease in pH because of lactate accumulation in the sarcoplasm and the cascade of reactions leading to muscle tissue damage. [ABSTRACT FROM AUTHOR]

The neonatal isoform of the sarcoplasmic/endoplasmic reticulum Ca ATPase 1 (SERCA1b) is a dominant Ca pump in the young fibers of regenerating muscle. In vivo transfection of about 1% of the fibers with SERCA1b RNAi plasmid resulted in no apparent change in the transfected fibers, but enhanced the increase of fresh weight and fiber size in the whole regenerating rat soleus muscle, until the normal size was reached. Co-transfection of calcineurin inhibitor cain/cabin-1 with SERCA1b RNAi was sufficient to cut down the widespread growth stimulation, but the subsequent transfection of cain into the SERCA1b RNAi transfected muscle did not inhibit muscle growth. The SERCA1b RNAi preferably upregulated the expression of the NFAT reporter lacZ compared to controls when co-transfected into the fibers. Notably, perimuscular injection of interleukin-4 (IL-4) antibody but not that of an unrelevant antibody completely abolished the growth-promoting effect of SERCA1b RNAi. This indicates that silencing SERCA1b in a few fibers stimulates the calcineurin-NFAT-IL-4 pathway and fiber growth in the whole regenerating soleus. These results suggest the presence of an autocrine-paracrine coordination of growing muscle fibers, and put forward a new method to stimulate skeletal muscle regeneration. [ABSTRACT FROM AUTHOR]

Copyright of Acta Facultatis Educationis Physicae Universitatis Comenianae is the property of Comenius University in Bratislava and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study investigate the protective effect of aqueous root extract of Desmodium gangeticum in preserving mitochondrial and sarcoplasmic ATPase during ischemia reperfusion injury. The isolated rat hearts in both drug and control group were subjected to warm ischemia (37°), followed by reperfusion with the Langendorff perfusion system. The aqueous root extract of Desmodium gangeticum (L) at a dose of 50 mg/kg body weight was found to be effective in the rat heart for the management of ischemic reperfusion injury. Physiological parameters were significantly (P<0.05) improved in drug treated rat hearts. Creatine phosphokinase in coronary perfusate found to be declined. Moreover, sarcoplasmic ATPase and mitochondrial enzymes were significantly (P<0.05) improved in drug treated rat hearts. In fact, histological analysis of the myocardium also suggested an improved ultra structure in Desmodium gangeticum treated rat heart. These results suggest that Desmodium gangeticum aqueous root extract can preserve the mitochondrial and sarcoplasmic ATPase in the myocardium, resulting in the improvement of cardiac function after ischemia reperfusion injury. [ABSTRACT FROM AUTHOR]

The hydrolysis of sarcoplasmic proteins during the growth of Lactobacillus plantarum CRL 681 isolated from fermented sausage was evaluated. Fermentation was carried out in a meat model system under controlled pH conditions (pH 4.0 and 6.0) at 30C for 96 h. The ability of this strain to grow and degrade soluble meat proteins at both assayed pHs was demonstrated. Results showed that sarcoplasmic protein hydrolysis at pH 4.0, as occurring during sausage fermentation, can be attributed to the combined action of acidic meat endogenous proteases, L. plantarum CRL 681 proteolytic activity and acid-induced changes arising from the bacterial fermentative metabolism. On the other hand, bacterial proteolysis was mainly involved on the hydrolytic changes observed at pH 6.0. PRACTICAL APPLICATIONS Lactobacillus plantarum CRL 681 isolated from Argentinean sausages showed to display technological metabolic traits such as high acidification rate, proteolytic and peptidase activity, biogenic amines degradation and absence of amino acid decarboxylase activity which can beneficially affect the quality and safety of fermented sausages. In addition, from the results of this study, L. plantarum CRL 681 acidogenic metabolism not only would assure hygienic quality of fermented sausages but would increase free amino acids and peptides release from meat proteins. As a whole, this strain has the potential to be successfully used as starter culture to improve final product quality. [ABSTRACT FROM AUTHOR]

Structural changes and functional properties of threadfin bream ( Nemipterus sp.) sarcoplasmic proteins (TB-SP) subjected to various pH conditions (pH 3, 5, 6.3, 9, and 12) after subsequent pH readjustment to pH 7 were investigated. Fourier transform infrared spectroscopy revealed the loss of α-helical and β-sheet structures of TB-SP after being subjected to pH 3 or pH 12 treatments. The extent of structural and conformational changes of TB-SP subjected to pH 3 was greater than alkaline pHs (pH 9, 12) and pH 5, respectively. The water holding capacity of lyophilized TB-SP treated at pH 3 and pH 12 increased about 6.5- and 5.4-fold, respectively, as compared to the crude counterpart. Both acid and alkaline pH treatments increased fat absorption capacity of lyophilized sample about 2-fold, but drastically decreased its solubility. The water soluble fraction of extremely acidic (pH 3→7) and alkaline (pH 12→7) samples exhibited higher oil binding capacity as measured by diphenylhexatriene fluorescence and emulsifying activity. A gel-like structure was formed when water-soluble fraction of crude TB-SP and those subjected to moderate pHs (pH 5, 9) at 2 mg/mL was prepared for the emulsion containing 50% oil (v/v). Functional properties of TB-SP varied, depending on the pH-adjustment process applied. [ABSTRACT FROM AUTHOR]

The oxidation of myofibrillar and sarcoplasmic proteins of thin-lipped mullet (Liza ramada ) in different ages during refrigerated storage (4C), and in vitro oxidation of muscle after 2 and 24 h incubation with Fe+ 2 /H2O2 at 4C were evaluated by means of protein carbonyl content. Changes in myofibrillar and sarcoplasmic proteins were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The carbonyl content of myofibrillar proteins exhibited a regular increase at 2 years of age during the refrigerated storage for 10 days (P < 0.05), and increased at 4 and 6 years of age after 5 days of cold storage (P > 0.05), and then did not significantly change between 5 and 10 days of storage (P > 0.05). Sarcoplasmic proteins showed a decrease in the carbonyl content at 2 years of age during 10 days of storage. However, no significant changes were observed in carbonyl content of sarcoplasmic proteins at 4 and 6 years of age (P > 0.05). An increase in carbonyl content of whole muscle, but not statistically significant, was found at 2, 4 and 6 years of age during 10 days of cold storage. There were no significant differences in oxidation of thin-lipped gray mullet proteins in all ages between 2 and 24 h of incubation with Fenton-like oxidation system (Fe+ 2 SO4/H2O2) at 4C (P < 0.05). However, there was a tendency to find an increase in carbonyl content in all ages after 24 h of incubation. Electrophoretic studies in the presence and absence of β-mercaptoethanol showed that high-molecular weight polymers via disulfide cross-linking and/or degradation/digestion by proteolysis could be formed in the myofibrillar proteins in different ages. Slight changes were observed in sarcoplasmic proteins of thin-lipped gray mullet both in the absence and presence of a disulfide-splitting agent. These results suggest that there is a probable link between protein oxidation and protelytic degradation of myofibrillar proteins during postmortem storage, and the effects of cold storage on oxidation and possible changes in myofibrillar and sarcoplasmic proteins could be changed depending on ages in same species. PRACTICAL APPLICATIONS The degradation of muscle proteins caused by proteolysis is one of the most important quality attributes of fish muscle throughout cold storage. However, knowledge about the effect of oxidative process on proteins and their effect on postmortem quality of fish is less known. In this study, we found a probable link between protein oxidation and degradation of thin-lipped mullet myofibrillar proteins, and their proteolysis may be stimulated by oxygen radicals during postmortem storage. These determinations are important to prevent protein degradation and improve the shelf life of thin-lipped mullet during postmortem storage. [ABSTRACT FROM AUTHOR]

This study examined the effect of adding common carp sarcoplasmic proteins (Sp- P) on the gel characteristics of threadfin bream surimi and kamaboko while maintaining constant moisture and myofibrillar levels. Based on the temperature sweep test, which is involved in heating of surimi gel from 10 to 80 °C to monitor the viscoelastic properties, at temperature range of 40 to 50 °C, the decrease level (depth of valley) in storage modulus (G′) thermograph was in proportion to the concentration of added Sp- P. Storage modulus (G′) showed greater elasticity after adding Sp- P compared with the control without Sp- P. Furthermore, the breaking force and distance and consequently gel strength of the resultant kamaboko were improved significantly ( P > 0.05). Thus, added Sp- P did not interfere with myofibrillar proteins during sol–gel transition phase but associated with textural quality enhancement of resultant kamaboko; however, addition of Sp- P from the dark muscle of the carp decreased the whiteness of the resultant surimi. Furthermore, according to the SEM micrographs, the gel strength could not be associated with either the number of polygonal structures/mm2 or the area of the polygonal structures in the kamaboko gel microstructure. [ABSTRACT FROM AUTHOR]

The degree to which lipid and myoglobin (Mb) oxidation processes interact in meat can be species-specific. We investigated the effects of beef and pork sarcoplasmic extracts containing different Mb concentrations on lipid oxidation in a liposome system. Sarcoplasm was extracted from beef and pork longissimus dorsi and psoas major muscles. Beef sarcoplasm was diluted with 0.1 M phosphate buffer to obtain a Mb concentration equivalent to that in pork sarcoplasm. Conversely, equine heart Mb was added to pork sarcoplasm to match the myoglobin concentration of beef sarcoplasm. This resulted in beef and pork sarcoplasms, each with 2 different Mb concentrations for the longissimus (0.02 mM and 0.07 mM) and psoas (0.05 and 0.12 mM). Sarcoplasm (or phosphate buffer control) was incorporated within a phosphatidylcholine liposome preparation and incubated at 25°C. Thiobarbituric acid reactive substances (TBARS) were measured at 0, 30, 60, 90, and 120 min of incubation. Regardless of species, greater Mb concentration within the sarcoplasm increased lipid oxidation ( P < 0.05). Across muscles, pork sarcoplasm had lower TBARS values than beef sarcoplasm ( P < 0.05). Our results suggest that pork sarcoplasm has a lesser effect on lipid oxidation than beef sarcoplasm for a common Mb concentration. However, increased myoglobin concentration within sarcoplasm promotes lipid oxidation regardless of species. [ABSTRACT FROM AUTHOR]

The ability of small heat shock proteins (sHSP) at preventing the aggregation and precipitation of unfolded and misfolded proteins because of changes in pH and temperature is widely recognised. The performance of sHSP from bovine lens extract at protecting sarcoplasmic proteins from heat induced denaturation and aggregation was compared with other chaperones including bovine serum albumin, αs-casein, β-casein and a synthetic peptide based upon αA-crystallin (AAC). Beef sarcoplasmic proteins were heated in the presence or absence of exogenous chaperone and the solubility, surface hydrophobicity and enzymatic activities of the sarcoplasmic proteins was determined. Lens extract prevented the aggregation of sarcoplasmic proteins, maintaining solubility and clarity up to 65 °C relative to 60 °C for β-casein. By contrast, αs- and β-casein proteins protected the activity of endogenous enzymes at temperatures between 37 °C and 52 °C, unlike lens sHSP. Our findings support the addition of casein proteins as potential thermal stabilisers of meat proteins in food systems. [ABSTRACT FROM AUTHOR]

The skeletal muscle Ca2+ release channel (RyR1), a homotetramer, regulates the release of Ca2+ from the sarcoplasmic reticulum to initiate muscle contraction. In this work, we have delineated the RyR1 monomer boundaries in a subnanometer-resolution electron cryomicroscopy (cryo-EM) density map. In the cytoplasmic region of each RyR1 monomer, 36 α-helices and 7 β-sheets can be resolved. A β-sheet was also identified close to the membrane-spanning region that resembles the cytoplasmic pore structures of inward rectifier K+ channels. Three structural folds, generated for amino acids 12-565 using comparative modeling and cryo-EM density fitting, localize close to regions implicated in communication with the voltage sensor in the transverse tubules. Eleven of the 15 disease-related residues for these domains are mapped to the surface of these models. Four disease-related residues are found in a basin at the interfaces of these regions, creating a pocket in which the immunophilin FKBP12 can fit. Taken together, these results provide a structural context for both channel gating and the consequences of certain malignant hyperthermia and central core disease-associated mutations in RyR1. [ABSTRACT FROM AUTHOR]

α-Actinin release from the myofibrillar protein fraction to the sarcoplasm can be considered as an accurate proteolysis index in seafood muscle. The main objective of the present study was to develop a specific enzyme-linked immunosorbent assay (ELISA), based on the use of a monoclonal antibody against α-actinin to evaluate the degree of proteolysis in two different chilled fish species – European hake ( Merluccius merluccius) and turbot ( Psetta maxima) – kept under two different storage systems: flake ice and slurry ice. Comparison with sensory assessment, K-value and sarcoplasmic protein profiles was carried out. A different degree of proteolysis could be observed in both fish species; thus, the immunoassay was shown to be useful in monitoring the protein degradation events in hake muscle especially under flake ice storage. In the case of turbot, as very low proteolysis development could be obtained, the assay was not suitable for assessing quality changes. A different break point of immunoassay values for each fish species is suggested. [ABSTRACT FROM AUTHOR]

Protecting the myocardium from the risk of acute ischemia during heart surgery is still an unsolved problem; the problem is even more open and more pressing in pediatric heart surgery. To meet this greater risk it is advisable to use a cardioplegic solution with a composition that is better suited to the particular morphofunctional conditions of the myocardium in the child, i.e., a solution offering greater protection. To this purpose the authors experimented with Celsior cardioplegic solution during heart surgery in children to evaluate the efficacy compared to the standard St. Thomas solution. In this comparative study 15 children were treated with Celsior cardioplegic solution and 15 others with St. Thomas cardioplegic solution. Each patient underwent 2 biopsies of the myocardium, the first before cardioplegic treatment and the second immediately after reperfusion.In both groups, focal lesions involving both the cardiomyocytes and the vascular-stromal structures were randomly found. The former had undergone a necrotic-regressive process with changes in the myofibrils and the mitochondria. The vascular–stromal structures showed changes in the permeability of the capillary endothelia, with interstitial edema. The results show the lesions to be similar in the 2 groups both on a quality and quantitative level. [ABSTRACT FROM AUTHOR]

The article describes an unusual case of abnormal accumulated glycogen and sarcoplasmic masses in a Spanish-bred filly. Based on the histochemical and ultrastructural findings conducted, the authors asserted that the filly had a neuromuscular disorder characterized by sarcoplasmic masses with abnormal accumulations of glycogen after observing the presence of sarcoplasmic masses in glycolytic myofibers.

The sonic muscle of type 1 male midshipman fish produces loud and enduring mating calls. Each sonic muscle fiber contains a tubular contractile apparatus with radially arranged myofibrillar plates encased in a desmin-rich cytoskeleton that is anchored to broad Z bands (~1.2 μm wide). Immunomicroscopy has revealed patches of myosin-rich “flares” emanating from the contractile tubes into the peripheral sarcoplasm along the length of the fibers. These flares contain swirls of thick filaments devoid of associated thin filaments. In other regions of the sarcoplasm at the inner surface of the sarcolemma and near Z bands, abundant ladder-like leptomeres occur with rungs every 160 nm. Leptomeres consist of dense arrays of filaments (~4 nm) with a structure that resembles myofibrillar Z band structure. We propose that flares and leptomeres are distinct filamentous arrays representing site-specific processing of myofibrillar components during the assembly and disassembly of the sarcomere. Recent reports that myosin assembles into filamentous aggregates before incorporating into the A band in the skeletal muscles of vertebrates and Caenorhabditis elegans suggest that sonic fibers utilize a similar pathway. Thus, sonic muscle fibers, with their tubular design and abundant sarcoplasmic space, may provide an attractive muscle model to identify myofibrillar intermediates by structural and molecular techniques. [ABSTRACT FROM AUTHOR]

The sarcoplasmic reticulum (SR) is composed of two fractions, the heavy fraction that contains proteins involved in Ca 2 + release, and the light fraction enriched in Ca 2 + -ATPase (SERCA), an enzyme responsible for Ca 2 + transport from the cytosol to the lumen of SR. It is known that in red muscle thyroid hormones regulate the expression of SERCA 1 and SERCA 2 isoforms. Here we show the effects of thyroid hormone on SERCA expression and distribution in light and heavy SR fractions from rabbit white and red muscles. In hyperthyroid red muscle there is an increase of SERCA 1 and a decrease of SERCA 2 expression. This is far more pronounced in the heavy than in the light SR fraction. As a result, the rates of Ca 2 + - ATPase activity and Ca 2 + -uptake by the heavy vesicles are increased. In hypothyroidism we observed a decrease in SERCA 1 and no changes in the amount of SERCA 2 expressed. This promoted a decrease of both Ca 2 + -uptake and Ca 2 + -ATPase activity. While the major differences in hyperthyroidism were found in the heavy SR fraction, the effects of hypothyroidism were restricted to light SR fraction. In white muscle we did not observe any significant changes in either hypo- or hyperthyroidism in both SR fractions. Thus, the regulation of SERCA isoforms by thyroid hormones is not only muscle specific but also varies depending on the subcellular compartment analyzed. These changes might correspond to the molecular basis of the altered contraction and relaxation rates detected in thyroid dysfunction. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Physiology & Pharmacology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)