Rat Leg Muscle Research Articles

Using the Probability Density Function-Based Channel-Combination Bloch-Siegert Method Realizes Permittivity Imaging at 3T.

Magnetic resonance electrical properties tomography (MR EPT) can retrieve permittivity from the B1+ magnitude. However, the accuracy of the permittivity measurement using MR EPT is still not ideal due to the low signal-to-noise ratio (SNR) of B1+ magnitude. In this study, the probability density function (PDF)-based channel-combination Bloch-Siegert (BSS) method was firstly introduced to MR EPT for improving the accuracy of the permittivity measurement. MRI experiments were performed using a 3T scanner with an eight-channel receiver coil. The homogeneous water phantom was scanned for assessing the spatial distribution of B1+ magnitude obtained from the PDF-based channel-combination BSS method. Gadolinium (Gd) phantom and rats were scanned for assessing the feasibility of the PDF-based channel-combination BSS method in MR EPT. The Helmholtz-based EPT reconstruction algorithm was selected. For quantitative comparison, the permittivity measured by the open-ended coaxial probe method was considered as the ground-truth value. The accuracy of the permittivity measurement was estimated by the relative error between the reconstructed value and the ground-truth value. The reconstructed relative permittivity of Gd phantom was 52.413, while that of rat leg muscle was 54.053. The ground-truth values of relative permittivity of Gd phantom and rat leg muscle were 78.86 and 49.04, respectively. The relative error of average permittivity was 33.53% for Gd and 10.22% for rat leg muscle. The results indicated the high accuracy of the permittivity measurement using the PDF-based channel-combination BSS method in MR EPT. This improvement may promote the clinical application of MR EPT technology, such as in the early diagnosis of cancers.

Micromagnetic stimulation (µMS) dose-response of the rat sciatic nerve

Objective. The objective of this study was to investigate the effects of micromagnetic stimuli strength and frequency from the Magnetic Pen (MagPen) on the rat right sciatic nerve. The nerve’s response was measured by recording muscle activity and movement of the right hind limb. Approach. The MagPen was custom-built to be stably held over the sciatic nerve. Rat leg muscle twitches were captured on video, and movements were extracted using image processing algorithms. EMG recordings were also used to measure muscle activity. Main results. The MagPen prototype, when driven by an alternating current, generates a time-varying magnetic field, which, according to Faraday’s law of electromagnetic induction, induces an electric field for neuromodulation. The orientation-dependent spatial contour maps of the induced electric field from the MagPen prototype have been numerically simulated. Furthermore, in this in vivo work on µMS, a dose-response relationship has been reported by experimentally studying how varying the amplitude (Range: 25 mV p-p through 6 V p-p) and frequency (range: 100 Hz through 5 kHz) of the MagPen stimuli alters hind limb movement. The primary highlight of this dose-response relationship (repeated over n rats, where n = 7) is that for a µMS stimuli of higher frequency, significantly smaller amplitudes can trigger hind limb muscle twitch. This frequency-dependent activation can be justified by Faraday’s Law, which states that the magnitude of the induced electric field is directly proportional to the frequency. Significance. This work reports that µMS can successfully activate the sciatic nerve in a dose-dependent manner. The impact of this dose-response curve addresses the controversy in this research community about whether the stimulation from these μcoils arise from a thermal effect or micromagnetic stimulation. MagPen probes do not have a direct electrochemical interface with tissue and therefore do not experience electrode degradation, biofouling, and irreversible redox reactions like traditional direct contact electrodes. Magnetic fields from the μcoils create more precise activation than electrodes because they apply more focused and localized stimulation. Finally, unique features of µMS, such as the orientation dependence, directionality, and spatial specificity, have been discussed.

Wideband frequency-dependent dielectric properties of rat tissues exposed to low-intensity focused ultrasound in the microwave frequency range

Tissue dielectric properties can vary upon the incident of an acoustic wave. The goal of this study is to quantify this change due to the acoustoelectric effect (AE), and to obtain the frequency-dependent dielectric properties of tissues exposed to low-intensity focused ultrasound (LIFU). The dielectric properties of the blood, brain, chest muscle, heart, kidney, leg muscle, liver, lung, pancreas, and spleen of rats were measured by an open-ended coaxial probe method. The acoustic intensity of LIFU focus was 2.97 MPa (67.6 W/cm2), 3.95 MPa (120 W/cm2), and 5.17 MPa (204 W/cm2), respectively, and the measurement frequency band was 0.1–7.08 GHz. The measurement results show that with the LIFU modulation, the conductivity and dielectric constant decreased in the high-frequency band, and on the contrary, they increased in the low-frequency band, and the larger the acoustic intensity was, the more obvious the phenomenon was. This work contributes to a better understanding of the mechanisms by which ultrasound acts on the dielectric properties of biological tissues. It is expected that the findings from this study will provide a basis that the response of tissue to LIFU modulation can be monitored by noninvasive techniques such as microwave-induced thermoacoustic imaging (MTI) and microwave imaging, present a new idea for improving the endogenous contrast between different biological tissues in MTI and acoustoelectric imaging, and possibly lead to the development of a new imaging method based on the relaxation time of tissue after LIFU modulation.

Differentially expressed microRNAs during the differentiation of muscle-derived stem cells into insulin-producing cells, a promoting role of microRNA-708-5p/STK4 axis.

Stem cell therapy is a promising approach for diabetes via promoting the differentiation of insulin-producing cells (IPCs). This study aimed to screen the differentially expressed miRNAs (DEmiRNAs) during the differentiation of muscle-derived stem cells (MDSCs) into IPCs, and uncover the underlying function and mechanism of a specific DEmiRNA, miR-708-5p. MDSCs were successfully isolated from the leg muscle of rats, and were induced for IPCs differentiation through a five-stage protocol. miRNA microarray assay was performed for screening DEmiRNAs during differentiation. The features of MDSCs-derived IPCs were identified by qRT-PCR, flow cytometry, and immunofluorescence staining. The targeting of STK4 by miR-708-5p was examined by luciferase assay. The protein expression of STK4, YAP1, and p-YAP1 was determined by Western blot and immunofluorescence staining. MDSCs were successfully isolated and differentiated into IPCs. A total of 12 common DEmiRNAs were obtained during five-stage differentiation. Among them, miR-708-5p that highly expressed in MDSCs-derived IPCs was selected. Overexpression of miR-708-5p upregulated some key transcription factors (Pdx1, Ngn3, Nkx2.2, Nkx6.1, Gata4, Gata6, Pax4, and Pax6) involving in IPCs differentiation, and increased insulin positive cells. In addition, STK4 was identified as the target gene of miR-708-5p. miR-708-5p overexpression downregulated the expression of STK4 and the downstream phosphorylated YAP1. There were 12 DEmiRNAs involved in the differentiation of MDSCs into IPCs. miR-708-5p promoted MDSCs differentiation into IPCs probably by targeting STK4-mediated Hippo-YAP1 signaling pathway.

Effect of embedded metal fragments on urinary metal levels and kidney biomarkers in the Sprague-Dawley rat.

Wounds with embedded metal fragments are an unfortunate consequence of armed conflicts. In many cases the exact identity of the metal(s) and their long-term health effects, especially on the kidney, are not known. The aim of this study was to quantitate the urinary levels of metals solubilized from surgically implanted metal pellets and to assess the effect of these metals on the kidney using a battery of biomarker assays. Using a rodent model system developed in our Institute to simulate embedded fragment injuries, eight metals considered likely components of an embedded fragment wound were individually implanted into the gastrocnemius muscle of male Sprague-Dawley rats. The rats were followed for 12 months post-implantation with urine collected prior to surgery then at 1-, 3-, 6-, 9-, and 12-months post-implantation to provide a within-subjects cohort for examination. Urinary metal levels were determined using inductively coupled plasma-mass spectrometry and urinary biomarkers assessed using commercially available kits to determine metal-induced kidney effects. With few exceptions, most of the implanted metals rapidly solubilized and were found in the urine at significantly higher levels than in control animals as early as 1-month post-implantation. Surprisingly, many of the biomarkers measured were decreased compared to control at 1-month post-implantation before returning to normal at the later time points. However, two metals, iron and depleted uranium, showed increased levels of several markers at later time points, yet these levels also returned to normal as time progressed. This study showed that metal pellets surgically implanted into the leg muscle of Sprague-Dawley rats rapidly solubilized with significant levels of the implanted metal found in the urine. Although kidney biomarker results were inconsistent, the changes observed along with the relatively low amounts of metal implanted, suggest that metal-induced renal effects need to be considered when caring for individuals with embedded metal fragment wounds.

Chemical exchange rotation transfer imaging of phosphocreatine in muscle.

In chemical exchange saturation transfer (CEST) imaging, the signal at 2.6 ppm from the water resonance in muscle has been assigned to phosphocreatine (PCr). However, this signal has limited specificity for PCr since the signal is also sensitive to exchange with protein and macromolecular protons when using some conventional quantification methods, and will vary with changes in the water longitudinal relaxation rate. Correcting for these effects while maintaining reasonable acquisition times is challenging. As an alternative approach to overcome these problems, here we evaluate chemical exchange rotation transfer (CERT) imaging of PCr in muscle at 9.4 T. Specifically, the CERT metric, AREXdouble,cpw at 2.6 ppm, was measured in solutions containing the main muscle metabolites, in tissue homogenates with controlled PCr content, and in vivo in rat leg muscles. PCr dominates CERT metrics around 2.6 ppm (although with nontrivial confounding baseline contributions), indicating that CERT is well-suited to PCr specific imaging, and has the added benefit of requiring a relatively small number of acquisitions.

Effects of genistein on N-glycolylneuraminic acid content in rats and the interaction with sialyl transferase

To investigate the effects of genistein (Gen) on the biosynthesis of N-glycolylneuraminic acid (Neu5Gc) in rats, 80 4-week-old male SD rats were randomly equally into the control and genistein groups. The rats of control and genistein groups were fed 5% ethanol and 300 mg/(kg·d) genistein respectively by gavage. The contents of Neu5Gc in hind leg muscle, kidney and liver tissues of rats were measured by using high performance liquid chromatography coupled with fluorescence detector (HPLC/FLD), and the mechanism of inhibition of Neu5Gc synthesis was investigated by using the molecular docking of Gen and sialyltransferase. On the 15th day, the content of Neu5Gc in hind leg muscle and liver tissues decreased 13.77% and 15.45%, respectively, and there was no significant change in the content of Neu5Gc in kidney tissues. On the 30th day, the content of Neu5Gc in liver tissues decreased 13.35%, however, there was no significant change in the content of Neu5Gc in kidney tissues and Neu5Gc was not detected in hind leg muscle. The content of Neu5Gc in hind leg muscle, kidney and liver tissues decreased respectively 32.65%, 32.78%, 16.80% and 12.72%, 11.42%, 12.30% while rats fed on the 45th and the 60th days. Genistein has formed the hydrogen bond with sialyltransferase activity site residues His319, Ser151, Gly293, Thr328 and formed a hydrophobic interactions with the residues His302, His301, Trp300, Ser271, Phe292, Thr328, Ser325 and Ile274. The results of molecular docking indicated that the weak intermolecular interaction was the main cause of genistein inhibiting sialyltransferase activity. The research results provided an experimental basis for the subsequent reduction of Neu5Gc in red meat before slaughter.

The effect of different surface treatment methods on the physical, chemical and biological performances of a PGA scaffold.

In order to improve the adhesion between a PGA scaffold and islet cells, it is necessary to find a suitable method to modify the scaffold. In this study, the PGA scaffold surface was modified by plasma, polylysine coating and plasma combined with polylysine coating (P–P-PGA). The surface adhesion of the modified PGA scaffold was examined, and the stretchability and infiltration of the PGA scaffold were also tested. Then, the PGA scaffold treated under the optimal treatment conditions was selected to co-culture with rat islet cells, and the survival activity of the rat islet cells on the untreated PGA scaffold and the P–P-PGA scaffold was examined via the MTT method. Rhodamine staining and DAPI staining were used to detect the number of islet cells adhered to four groups of scaffolds at different culture time points. The PGA-islet graft in the leg muscle of rats was stained with HE to perform the PGA-islet graft pathological examination. The experimental results showed that when the plasma treatment power was 240 W, the processing time was 4 min; the concentration of the polylysine coating solution was 2 mg ml−1, the tensile strength of the PGA scaffold was 320.45 MPa and the amount of infiltration of the PGA scaffold by the serum medium presented the maximum value: 3.17 g g−1. The MTT survival activity test results showed that after 3 d of culture, the survival activity of the islet cells of the treated PGA scaffold culture group (2.02 ± 0.13) was significantly different from the survival activity of the islet cells of the untreated PGA scaffold culture group (1.93 ± 0.10). The survival activities of the islet cells in the experimental groups (1.60 ± 0.13, 1.40 ± 0.12) were still higher than those of the control groups (0.96 ± 013, 0.69 ± 0.09) at 15 and 21 d. The results of the rhodamine and DAPI staining showed that with the increase in culture time, the number of the adherent cells in each group increased, and the number of the adherent islet cells in the experimental group was higher than that in the untreated group. The HE staining results showed that the islet cells on the P–P-PGA scaffold were more than those on the untreated PGA scaffold. After modification of the PGA scaffold, the adhesion of the islet cells improved, which was conducive to the growth of islet cells. These results confirmed that the plasma combined with polylysine coating treatment could enhance the adhesion of the PGA scaffold surface, so that the scaffold and the islet cells exhibited better adhesion and biocompatibility, and the modified PGA scaffold (P–P-PGA) could be used as a promising islet cell scaffold.

Hydroxysafflor yellow A attenuates the expression of inflammatory cytokines in acute soft tissue injury

We examined the effect of hydroxysafflor yellow A (HSYA) on the inflammatory response to strike-induced acute soft tissue injury in rats. Soft tissue injury was induced in rat leg muscles using a strike hammer, followed by intraperitoneal administration of HSYA at 16, 32, or 64 mg/kg. After 24 h, the rats were anaesthetized, blood and muscle samples were taken. Plasma levels of interleukin (IL)-6, IL-1β, and tumour necrosis factor (TNF)-αwere measured by enzyme-linked immunosorbent assay. Total RNA and protein were isolated from muscle tissue to determine the mRNA levels of IL-6, IL-1β, TNF-α, vascular cell adhesion molecule (VCAM)-1, and intercellular adhesion molecule (ICAM)-1, and the protein level of phosphorylated p38 mitogen-activated protein kinase (MAPK). Nuclear factor (NF)-κB expression was determined by muscle histopathology and immunohistochemistry. HSYA attenuated pathologic changes instrike-induced soft tissue inflammation. Treatment with HSYA also alleviated strike-induced increases in TNF-α, IL-1β, IL-6, VCAM-1, and ICAM-1mRNA levels and inhibited the increased activation of NF-κB and phosphorylation of p38 MAPK in muscle tissue. These findings suggest that HSYA effectively inhibits strike-induced inflammatory signal transduction in rats.

Exercise modulates synaptic acetylcholinesterase at neuromuscular junctions

Acetylcholinesterase plays a major role in neuromuscular transmission and is regulated by neuromuscular activity. Since fast-twitch motor units are recruited with increased motor demand, we examined acetylcholinesterase regulation in rat leg muscles following treadmill training. Total acetylcholinesterase and specifically the membrane-bound tetramer increased in exercised fast-, but not slow-twitch muscles, while other isoforms remained unchanged. Synaptic acetylcholinesterase increased markedly in neuromuscular junctions of trained fibers, without concomitant changes in synaptic acetylcholine receptor, thus elevating synaptic acetylcholinesterase/receptor ratios. Electron microscopy showed that acetylcholinesterase increased in postjunctional folds and primary cleft, where it was added adjacent to the postsynaptic muscle membrane. Thus, although the primary acetylcholinesterase at the neuromuscular junction is the collagen-tailed asymmetric isoform associated with synaptic basal lamina, physiological demands such as strenuous exercise, or potentially pathological conditions, can selectively recruit the membrane-bound acetylcholinesterase tetramer to the synapse for optimal synaptic transmission.

The Role of the Component Metals in the Toxicity of Military-Grade Tungsten Alloy.

Tungsten-based composites have been recommended as a suitable replacement for depleted uranium. Unfortunately, one of these mixtures composed of tungsten (W), nickel (Ni) and cobalt (Co) induced rhabdomyosarcomas when implanted into the leg muscle of laboratory rats and mice to simulate a shrapnel wound. The question arose as to whether the neoplastic effect of the mixture could be solely attributed to one or more of the metal components. To investigate this possibility, pellets with one or two of the component metals replaced with an identical amount of the biologically-inert metal tantalum (Ta) were manufactured and implanted into the quadriceps of B6C3F1 mice. The mice were followed for two years to assess potential adverse health effects. Implantation with WTa, CoTa or WNiTa resulted in decreased survival, but not to the level reported for WNiCo. Sarcomas in the implanted muscle were found in 20% of the CoTa-implanted mice and 5% of the WTa- and WCoTa-implanted rats and mice, far below the 80% reported for WNiCo-implanted mice. The data obtained from this study suggested that no single metal is solely responsible for the neoplastic effects of WNiCo and that a synergistic effect of the three metals in tumor development was likely.

Microvascular circulation at cool, normal and warm temperatures in rat leg muscles examined by histochemistry using Lycopersicon esculentum lectin

Local cooling and/or warming of the body are widely used for therapy. For safer and more effective therapy, microvascular hemodynamics needs to be clarified. To examine blood circulation in rat leg muscles at 20, 30, 37 and 40°C, fluorescein isothiocyanate (FITC)-labeled Lycopersicon esculentum lectin was injected into the cardiac ventricle. Endothelial cells of open and functioning blood vessels were labeled by this lectin for 3min and detected by immunostaining for lectin. The percentage of open and functioning capillaries of leg muscles by the avidin–biotin method was 89.8±3.3% at 37°C, while capillaries were unclear or unstained at 20 and 30°C, probably due to a decrease of blood flow. The results using the tyramide–dinitrophenol method were 58.6±15.0% at 20°C, 68.5±12.3% at 30°C, 83.8±5.7% at 37°C and 83.3±7.8% at 40°C. The value at 20°C was significantly different from those at 37 and 40°C. The results by the tyramide–biotin method were 85.5±5.3% at 20°C, 87.3±9.7% at 30°C, 94.7±3.6% at 37°C and 92.5±2.1% at 40°C. Based on these results, it was concluded that the blood flow of each capillary considerably decreased at 20 and 30°C and probably increased at 40°C, whereas the proportion of open and functioning capillaries was essentially unchanged.

Genotoxic changes to rodent cells exposed in vitro to tungsten, nickel, cobalt and iron.

Tungsten-based materials have been proposed as replacements for depleted uranium in armor-penetrating munitions and for lead in small-arms ammunition. A recent report demonstrated that a military-grade composition of tungsten, nickel, and cobalt induced a highly-aggressive, metastatic rhabdomyosarcoma when implanted into the leg muscle of laboratory rats to simulate a shrapnel wound. The early genetic changes occurring in response to embedded metal fragments are not known. In this study, we utilized two cultured rodent myoblast cell lines, exposed to soluble tungsten alloys and the individual metals comprising the alloys, to study the genotoxic effects. By profiling cell transcriptomes using microarray, we found slight, yet distinct and unique, gene expression changes in rat myoblast cells after 24 h metal exposure, and several genes were identified that correlate with impending adverse consequences of ongoing exposure to weapons-grade tungsten alloy. These changes were not as apparent in the mouse myoblast cell line. This indicates a potential species difference in the cellular response to tungsten alloy, a hypothesis supported by current findings with in vivo model systems. Studies examining genotoxic-associated gene expression changes in cells from longer exposure times are warranted.

Investigation of the nerve distribution pattern of leg muscles in rat

Information about the distribution of intramuscular nerve fibres within the skeletal muscles will enhance the understanding of their morphological structure and functions. This study was designed to examine the entire intramuscular nerve distribution pattern in rat leg muscles. The tibialis cranialis, tibialis caudalis, extensor digitorum longus, flexor digitorum longus, gastrocnemius, peroneus longus and brevis muscles were dissected from origo and insertion points under a surgical microscope in seven rats. These skeletal muscles from right hindlimbs were stained with Sihler's stain. The diameter of extramuscular and major nerve branches, number of major and minor nerve branches and anastomoses were measured and photographed under a stereomicroscope. In addition, serial sections were obtained from the left hindlimb muscles with S100 immunohistochemical staining and transferred to the computer to reconstruct images. A significant difference was found between the gastrocnemius and tibialis caudalis (p<0.001), flexor digitorum longus and tibialis caudalis (p<0.003), and peroneus longus and tibialis caudalis (p<0.049) with regard to the diameter of major branches. The gastrocnemius was significantly different from the flexor digitorum longus, peroneus longus, extensor digitorum longus, tibialis caudalis and tibialis cranialis with regard to the number of minor nerve branches (p<0.001). Knowledge of the branching pattern and some key landmarks, such as the number and diameter of major and minor nerve branches and the number of anastomoses between the nerve branches of skeletal muscles, is helpful in surgical or therapeutic interventions and botulinum toxin injections in areas of high extramuscular and intramuscular nerve density.

Temporal MRI characterization of gelatin/hyaluronic acid/chondroitin sulfate sponge for cartilage tissue engineering

A tri-copolymer sponge consisting of gelatin, hyaluronic acid, and chondroitin sulfate (GHC) was designed to mimic the cartilage environment in vivo for cartilage regeneration. The present study aimed to temporally characterize the magnetic resonance relaxation time of GHC constructs in vivo in a rodent heterotopic model. GHC sponges with cells (GHCc) or without cells (GHC) implanted in rat leg muscle were monitored using MRI (4.7 T MR scanner) on day 0, 7, 14, and 21 after implantation. The results revealed that the transverse relaxation time (T2) of GHC constructs decreased significantly over time when compared to the T2 of GHCc constructs. However, the longitudinal relaxation time (T1) of GHCc and GHC constructs remained stable. Moreover, hematoxylin and eosin and immunohistochemical staining with antibodies to S100 protein, and types I and II collagen showed that normal morphology, phenotype, and function of chondrocytes were preserved in the GHCc construct. Thus, we concluded that GHC constructs adequately support chondrocyte growth and function. On top of that, T2 may be a useful tool for monitoring cartilage regeneration in GHC constructs.

Identification of hemostatic genes expressed in human and rat leg muscles and a novel gene (LPP1/PAP2A) suppressed during prolonged physical inactivity (sitting)

BackgroundPartly because of functional genomics, there has been a major paradigm shift from solely thinking of skeletal muscle as contractile machinery to an understanding that it can have roles in paracrine and endocrine functions. Physical inactivity is an established risk factor for some blood clotting disorders. The effects of inactivity during sitting are most alarming when a person develops the enigmatic condition in the legs called deep venous thrombosis (DVT) or “coach syndrome,” caused in part by muscular inactivity. The goal of this study was to determine if skeletal muscle expresses genes with roles in hemostasis and if their expression level was responsive to muscular inactivity such as occurs in prolonged sitting.MethodsMicroarray analyses were performed on skeletal muscle samples from rats and humans to identify genes associated with hemostatic function that were significantly expressed above background based on multiple probe sets with perfect and mismatch sequences. Furthermore, we determined if any of these genes were responsive to models of physical inactivity. Multiple criteria were used to determine differential expression including significant expression above background, fold change, and non-parametric statistical tests.ResultsThese studies demonstrate skeletal muscle tissue expresses at least 17 genes involved in hemostasis. These include the fibrinolytic factors tetranectin, annexin A2, and tPA; the anti-coagulant factors TFPI, protein C receptor, PAF acetylhydrolase; coagulation factors, and genes necessary for the posttranslational modification of these coagulation factors such as vitamin K epoxide reductase. Of special interest, lipid phosphate phosphatase-1 (LPP1/PAP2A), a key gene for degrading prothrombotic and proinflammatory lysophospholipids, was suppressed locally in muscle tissue within hours after sitting in humans; this was also observed after acute and chronic physical inactivity conditions in rats, and exercise was relatively ineffective at counteracting this effect in both species.ConclusionsThese findings suggest that skeletal muscle may play an important role in hemostasis and that muscular inactivity may contribute to hemostatic disorders not only because of the slowing of blood flow per se, but also potentially because of the contribution from genes expressed locally in muscles, such as LPP1.

Intramuscular injection of soluble receptor for advanced glycation endproducts expression vector prevents the development of streptozotocin-induced diabetes mellitus in rats on high fat diet

In order to study if advanced glycation endproducts (AGE) in high-temperature cooked high fat diet could be the cause of type 2 diabetes, a expressing vector encoding soluble form of receptor for AGE (sRAGE) was injected intramuscularly, and the incidence of streptozotocin (STZ)-induced diabetes mellitus in rats on high fat diet were observed. Rat sRAGE gene, cloned to a pLNCX(2) expression vector (pLNCX(2) -sRAGE), was injected into the hind leg muscles of Sprague-Dawley rats. Rats were fed with high fat diet for 8 weeks before pLNCX(2) -sRAGE injection (designed as T group), or pLNCX2 (as H group), and rats on normal chow (as N group). The diet remained the same until end of the study. Serum malondialdehyde (MDA) and superoxide dismutase (SOD) levels were studied in one serial of rats (n = 8) under the treatment of different vectors without STZ injection. For a second serial of study (n = 20), rats were injected with 30 mg/kg STZ intraperitoneally 2 weeks after the second injection of vectors, and tail blood glucose was detected 1 week later. Malondialdehyde levels were found to be decreased 1 week after injection of sRAGE and lasted for at least 3 weeks after each injection. SOD activities were found to be increased slowly in the second week after each injection. As determined with fasting and random glycemia only two rats were in diabetic level (fasting glycemia ≥7.0 mmol/L and random glycemia ≥11.1 mmol/L) in T group while eight mice were in the diabetic level in H group. Intramuscular injection of sRAGE decreases the MDA level and increases SOD activities, and decreases the STZ-induced incidence of diabetes in rats in high fat diet.

Transversal stiffness of fibers and desmin content in leg muscles of rats under gravitational unloading of various durations

The aim of this research was the analysis of structural changes in various parts of the sarcolemma and contractile apparatus of muscle fibers by measuring their transversal stiffness by atomic force microscopy under gravitational unloading. Soleus, medial gastrocnemius, and tibialis anterior muscles of Wistar rats were the objects of the study. Gravitational unloading was carried out by antiorthostatic suspension of hindlimbs for 1, 3, 7, and 12 days. It was shown that the transversal stiffness of different parts of the contractile apparatus of soleus muscle fibers decreases during gravitational unloading in the relaxed, calcium-activated, and rigor states, the fibers of the medial gastrocnemius show no changes, whereas the transversal stiffness of tibialis anterior muscle increases. Thus the transversal stiffness of the sarcolemma in the relaxed state is reduced in all muscles, which may be due to the direct action of gravity as an external mechanical factor that can influence the tension on a membrane. The change of sarcolemma stiffness in activated fibers, which is due probably to the transfer of tension from the contractile apparatus, correlates with the dynamics of changes in the content of desmin.

In this issue

PROTEOMICSVolume 10, Issue 14 In this issue In this issue First published: 14 July 2010 https://doi.org/10.1002/pmic.201090062AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Following the firebomb The ancients got one thing right with their Aristotelian elements: Fire. Reactive oxygen species (ROS) are a universal element of life. The spark of fire that creates ATP is the result of completing the last hand-off in the relay of electrons that consumes our food in exchange for chemical energy. But, as Prometheus discovered, there was a price to be paid for giving man fire. But I digress; that's for Ancient History 101. Federova et al. chose to use rat legmuscle proteins as a system for studying the damage caused by and recovery from oxidative stress directed primarily at the amino acid tryptophan. Knowing the crystal structure of actin and tropomyosin, they were able to use MS/MS to determine the sensitivity of each trp residue to damage and the rate at which the cell repaired the damage caused by X-irradiation. pp. 2692–2700 Little snails grow up Snails are escargot in some parts of the world, but mostly they are agricultural pests. They are not enough of a pest to put them on the “genome to be sequenced” list, so Sun et al. took it upon themselves to at least get some proteomic data on early development of one species. Pomacea canaliculata, the golden apple snail, lays up to 8000 eggs per year. Development goes through several stages, initially without a shell, then developing a fully formed shell as it transitions from stage II to stage III. A number of other changes occur at the same time. Using 2-DE MS/MS, they detected ∼700 spots, 125 of which were abundant enough to examine further. They were sequenced then MS-BLASTed and MASCOTed; over 50% were identified. Some look like potential targets for control of the pests. pp. 2701–2711 Does your model lose its flavor in the forced layout overnight? Do your nodes and edges seem to all look alike? Do you get a headache after trying to remember differences between, say, the third and fourth layouts? Do you stop when you should GO? Then you need the smooth new clustered circular layout (CCL) software (Fung et al.). Compared with graphs generated by the old-fashioned force directed layout, the CCL does not suffer from irregularity in final layout and it does treat complementary information, e.g. Gene Ontology data, as real information, not simply as a name tag, and it can use colors intelligently for nodes and edges. The visibility of GO information also reveals the location of protein-protein clusters, bottleneck points at interfaces, and localization of proteins in organelles. pp. 2723–2727 Volume10, Issue14No. 14 July 2010 RelatedInformation

A Subpopulation of Rat Muscle Fibers Maintains an Assessable Excitation-Contraction Coupling Mechanism After Long-Standing Denervation Despite Lost Contractility

To define the time course and potential effects of electrical stimulation on permanently denervated muscle, we evaluated excitation-contraction coupling (ECC) of rat leg muscles during progression to long-term denervation by ultrastructural analysis, specific binding to dihydropyridine receptors, ryanodine receptor 1 (RYR-1), Ca channels and extrusion Ca pumps, gene transcription and translation of Ca-handling proteins, and in vitro mechanical properties and electrophysiological analyses of sarcolemmal passive properties and L-type Ca current (ICa) parameters. We found that in response to long-term denervation: 1) isolated muscle that is unable to twitch in vitro by electrical stimulation has very small myofibers but may show a slow caffeine contracture; 2) only roughly half of the muscle fibers with "voltage-dependent Ca channel activity" are able to contract; 3) the ECC mechanisms are still present and, in part, functional; 4)ECC-related gene expression is upregulated; and 5) at any time point, there are muscle fibers that are more resistant than others to denervation atrophy and disorganization of the ECC apparatus. These results support the hypothesis that prolonged "resting" [Ca] may drive progression of muscle atrophy to degeneration and that electrical stimulation-induced [Ca] modulation may mimic the lost nerve influence, playing a key role in modifying the gene expression of denervated muscle. Hence, these data provide a potential molecular explanation for the muscle recovery that occurs in response to rehabilitation strategies developed based on empirical clinical observations.