1,721,017 research outputs found
Nutrition and Regulation of Muscle Protein Synthesis
Full text link: Skeletal muscles are an indispensable actor for daily activities, playing an essential role in locomotion through both the control of posture and position and by joint stabilization [...]
Morphological evaluation of liposomal iron carriers
No full textIron is one of the most important elements for human, because it plays an essential role in many metabolic processes. However, it is also recognized to be dangerous for its detrimental effect inside human cells, where, in the absence of homeostatic balance, it can induce free radicals formation. Moreover, an excessive accumulation of iron in tissues can produce iron overload, a condition incompatible with life. The use of liposomes as carriers can represent an interesting iron therapy to improve iron bioavailability and reduce its negative effects, in particular during pregnancy. In this study, a morphological analysis has been performed on commercial liposome vesicles at various drying times, both in saline solution and in distilled water. Furthermore, to highlight their possible interaction or internalization in cells, liposomes have been administered to human hemopoietic U937 cells. Ultrastructural analyses confirm that vesicle morphology and size are comparable with classical liposomal structures. Products are stable during specimen preparation and drying. Additionally, they have a good ability to penetrate into cells, interacting with cytoplasmic organelles, without inducing, at least apparently, any ultrastructural damage
α-Actinin involvement in Z-disk assembly during skeletal muscle C2C12 cells in vitro differentiation
No full textα-Actinin is involved in the assembly and maintenance of muscle fibers. α-Actinin is required to cross-link actin filaments and to connect the actin cytoskeleton to the cell membrane and it is necessary for the attachment of actin filaments to Z-disks in skeletal muscle fibers and to dense bodies in smooth muscle ones. In addition to its mechanical role, sarcomeric α-actinin interacts with proteins involved in a variety of signaling and metabolic pathways.The aim of this work is to monitor Z-disk formation, in order to clear up the role of sarcomeric α-actinin in undifferentiated stage, after 4 days of differentiation (intermediate differentiation stage) and after 7 days of differentiation (fully differentiated stage). For this purpose, C2C12 murine skeletal muscle cells, grown in vitro, were analyzed at three time points of differentiation.Confocal laser scanner microscopy and transmission electron microscopy have been utilized for α-actinin immunolocalization.Both techniques reveal that in undifferentiated cells labeling appears uniformly distributed in the cytoplasm with punctate α-actinin Z-bodies. Moreover, we found that when differentiation is induced, α-actinin links at first membrane-associated proteins, then it aligns longitudinally across the cytoplasm and finally binds actin, giving rise to Z-disks. These findings evidence α-actinin involvement in sarcomeric development, suggesting for this protein an important role in stabilizing the muscle contractile apparatus
Three-dimensional apoptotic nuclear behavior analyzed by means of field emission in lens scanning electron microscope
Full text linkApoptosis is an essential biological function required during embryogenesis, tissue homeostasis, organ development and immune system regulation. It is an active cell death pathway involved in a variety of pathological conditions. During this process cytoskeletal proteins appear damaged and undergo an enzymatic disassembling, leading to formation of apoptotic features. This study was designed to examine the threedimensional chromatin behavior and cytoskeleton involvement, in particular actin re-modeling. HL-60 cells, exposed to hyperthermia, a known apoptotic trigger, were examined by means of a Field Emission in Lens Scanning Electron Microscope (FEISEM). Ultrastructural observations revealed in treated cells the presence of apoptotic patterns after hyperthermia trigger. In particular, three-dimensional apoptotic chromatin rearrangements appeared involving the translocation of filamentous actin from cytoplasm to the nucleus. FEISEM immunogold techniques showed actin labeling and its precise three-dimensional localization in the diffuse chromatin, well separated from the condensed one. The actin presence in dispersed chromatin inside the apoptotic nucleus can be considered an important feature, indispensable to permit the apoptotic machinery evolution
Holotomographic microscopy: A new approach to detect apoptotic cell features
No full textHolotomographic (HT) microscopy, combines two techniques, holography and tomography, and, in this way, it allows to quantitatively and noninvasively investigate cells and thin tissue slices, by obtaining three-dimensional (3D) images and by monitoring inner morphological changes. HT has indeed two significant advantages: it is label-free and low-energy light passes through the specimen with minimal perturbation. Using quantitative phase imaging with optical diffraction tomography, it can produce 3D images by measuring the refraction index (RI). Therefore, based on RI values, HT can provide structural and chemical cell information, such as dry mass values, morphological changes, or cellular membrane dynamics. In this study, suspended and adherent culture cells have been processed for HT analyses. Some of them have been treated with known apoptotic drugs or pro-oxidant agents and cell response has been investigated both by conventional microscopic approaches and by HT. The ultrastructural and fluorescence images have been compared to those obtained by HT and their congruence has been discussed, with particular attention to apoptotic cell death and on correlated plasma membrane changes. HT appears a valid approach to further characterize well-known apoptotic features such as cell blebbing, chromatin condensation, micronuclei, and apoptotic bodies. Taken together, our data demonstrate that HT appears suitable to highlight suspended or adherent cell behavior under different conditions. In particular, this technique appears an important new tool to distinguish healthy cells from the apoptotic ones, as well as to monitor outer and inner cell changes in a rapid way and with a noninvasive, label-free, approach
Polyphenols and their potential role in preventing skeletal muscle atrophy
No full textSkeletal muscle atrophy is the consequence of various conditions, such as disuse, denervation, fasting, aging, and disease. Even if the underlying molecular mechanisms are still not fully understood, an elevated oxidative stress related to mitochondrial dysfunction has been proposed as one of the major contributors to skeletal muscle atrophy. Researchers have described various forms of nutritional supplementation to prevent oxidative stress-induced muscle wasting. Among a variety of nutrients, attention has also focused on polyphenols, a wide range of plant-based compounds with antioxidant and inflammatory properties, many of which have beneficial effects on human health and might retard skeletal muscle loss and function impairment. The purpose of this review is to describe polyphenol actions in skeletal muscle atrophy prevention. Published articles from the last 10 years were searched on PubMed and other databases. Polyphenols are important molecules that should be considered when discussing possible strategies against muscle atrophy. In particular, the collected studies describe, for each polyphenol subclass, the beneficial effect on muscle mass preservation in various skeletal muscle disorders. In these examples, the polyphenol compounds appear to mainly act by reversing mitochondrial dysfunction. Given that the current information on polyphenols is mostly restricted to basic studies, more comprehensive research and additional studies should be performed to clarify their mechanisms of action in improving skeletal muscle functions during atrophy
Further considerations on in vitro skeletal muscle cell death
No full textThe present review discusses the apoptotic behavior induced by chemical and physical triggers in C2C12 skeletal muscle cells, comparing myoblast to myotube sensitivity, and investigating it by means of morphological, biochemical and cytofluorimetric analyses. After all treatments, myotubes, differently from myoblasts, showed a poor sensitivity to cell death. Intriguingly, in cells exposed to staurosporine, etoposide and UVB radiation, apoptotic and normal nuclei within the same fibercould be revealed. The presence of nuclear-dependent "territorial" death domains in the syncytium could explain a delayed cell death of myotubes compared to mononucleated cells. Moreover, autophagic granules abundantly appeared in myotubes after each treatment. Autophagy could protect muscle cell integrity against chemical and physical stimuli, making C2C12 myotubes, more resistant to cell death induction
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