Tension Development Research Articles

Injury Rate of the Bronze Age Population from the Lower Volga Area

Introduction. The research objective is to determine and analyze data on traumatic phenomena found in the bones of the Bronze Age population originating from the burial sites of the Lower Volga area. Methods. The identification of traumatic injuries in anthropological materials was based on the works and recommendations in the field of special traumatology and pathology used in forensic medicine and bioarchaeological reconstructions. Statistical analysis was carried out using one-dimensional methods and nonparametric Mann-Whitney and Kruskal-Wallis criteria. Analysis. The study of paleoanthropological materials of the Early Bronze Age shows that injuries are found only on skulls. The total injuries of the adult population in the group are at the level of 15.2%. Of the 5 injuries on the bones of the Early Bronze Age, 1 belongs to a woman and 4 – to men. Severe injuries are discovered in adult individuals. General injuries are not numerous and reach 24.8%. In the series of the Late Bronze Age, injuries on the bone remains of children are also not detected. The frequency of occurrence of traumatic objects on anthropological materials of II millennium BC is insignificant, only 18 cases, which is 16.1% of the total number of adult individuals. Results. In the studied series, sex dimorphism and differences in the nature of distribution of injuries between groups of different ages are not statistically revealed, which indicates similar social roles of the male and female population in the Bronze Age. No injuries are detected in children. The frequency of perimortem injuries is extremely low. Non-lethal (uniform, with traces of healing) injuries on the skull bones and postcranial skeleton dominate in the series, which indicates a similar level of technological development and medical knowledge in the Bronze Age population. Injuries of the Bronze Age of the Lower Volga region can be described as every day or civilian trauma due to the development of labor production or social tension in the groups.

S100A4 is activated by RhoA and catalyses the polymerization of non-muscle myosin, adhesion complex assembly and contraction in airway smooth muscle.

S100A4 is expressed in many tissues, including smooth muscle (SM), but its physiologic function is unknown. S100A4 regulates the motility of metastatic cancer cells by binding to non-muscle (NM) myosin II. Contractile stimulation causes the polymerization of NM myosin in airway SM, which is necessary for tension development. NM myosin regulates the assembly of adhesion junction signalling complexes (adhesomes) that catalyse actin polymerization. In airway SM, ACh (acetylcholine) stimulated the binding of S100A4 to the NM myosin heavy chain, which was catalysed by RhoA GTPase via the RhoA-binding protein, rhotekin. The binding of S100A4 to NM myosin was required for NM myosin polymerization, adhesome assembly and actin polymerization. S100A4 plays a critical function in the regulation of airway SM contraction by catalysing NM myosin filament assembly. The interaction of S100A4 with NM myosin may also play an important role in the physiologic function of other tissues. S100A4 binds to the heavy chain of non-muscle (NM) myosin II and can regulate the motility of crawling cells. S100A4 is widely expressed in many tissues including smooth muscle (SM), although its role in the regulation of their physiologic function is not known. We hypothesized that S100A4 contributes to the regulation of contraction in airway SM by regulating a pool of NM myosin II at the cell cortex. NM myosin II undergoes polymerization in airway SM and regulates contraction by catalysing the assembly of integrin-associated adhesome complexes that activate pathways that catalyse actin polymerization. ACh stimulated the interaction of S100A4 with NM myosin II in airway SM at the cell cortex and catalysed NM myosin filament assembly. RhoA GTPase regulated the activation of S100A4 via rhotekin, which facilitated the formation of a complex between RhoA, S100A4 and NM myosin II. The depletion of S100A4, RhoA or rhotekin from airway SM tissues using short hairpin RNA or small interfering RNA prevented NM myosin II polymerization as well as the recruitment of vinculin and paxillin to adhesome signalling complexes in response to ACh, and inhibited actin polymerization and tension development. S100A4 depletion did not affect ACh-stimulated SM myosin regulatory light chain phosphorylation. The results show that S100A4 plays a critical role in tension development in airway SM tissue by catalysing NM myosin filament assembly, and that the interaction of S100A4 with NM myosin in response to contractile stimulation is activated by RhoA GTPase. These results may be broadly relevant to the physiologic function of S100A4 in other cell and tissue types.

Effect of Oxygen Free Radicals on Cardiac Contractile Activity and Sarcolemmal Na(+)-Ca(2+) Exchange.

BACKGROUND: Although oxygen free radicals have been shown to induce myocardial cell damage and cardiac dysfunction, the exact mechanism by which these radicals affect the heart function is not clear. Since the occurrence of intracellular Ca(2+) overload is critical in the genesis of cellular damage and cardiac dysfunction, and since the sarcolemmal Na(+)-Ca(2+) exchange is intimately involved in Ca(2+) movements in myocardium, this study was undertaken to examine the effects of oxygen free radicals on the relationship between changes in cardiac contractile force development and sarcolemmal Na(+)-Ca(2+) exchange activity. METHODS AND RESULTS: Isolated rat hearts were perfused with a medium containing xanthine plus xanthine oxidase for different times, and changes in contractile force as well as sarcolemmal Na(+)-(2+) exchange activity were monitored. Perfusion of the heart with xanthine plus xanthine oxidase resulted in a transient increase followed by a marked decrease in contractile activity; the resting tension was markedly increased. The xanthine plus xanthine oxidase-induced depression in developed tension, rate of contraction, and rate of relaxation, except the transient increase in contractile activity, was prevented by the addition of catalase, but not by superoxide dismutase, in the perfusion medium. A time-dependent depression in sarcolemmal Na(+)-Ca(2+) was also evident upon perfusing the heart with xanthine plus xanthine oxidase. This depression in Na(+)-dependent Ca(2+) uptake was associated with a decrease in the maximal velocity of reaction without any changes in the affinity of Na(+)-Ca(2+) exchanger for Ca(2+). The presence of catalase, unlike superoxide dismutase, prevented the decrease in sarcolemmal Na(+)-Ca(2+) exchange activity in hearts perfused with xanthine plus xanthine oxidase. CONCLUSIONS: The results support the view that a depression in the sarcolemmal Na(+)-Ca(2+) exchange activity may contribute to the occurrence of intracellular Ca(2+) overload and subsequent decrease in contractile activity. Furthermore, these actions of xanthine plus xanthine oxidase in the whole heart appear to be a consequence of H(2)O(2) production rather than the generation of superoxide radicals.

Digital spaces of network aggression: Muscovites ‘ perception of migrants

ABSTRACT The paper presents the analysis of speech perception and of the specific nature of communication between migrants and residents of Moscow, as reflected in the digital environment. The main focus is on conflictogenic digital zones, as well as methods for predicting and preventing conflicts. The development of algorithms to make predictions about users’ possible actions, the occurrence and prevention of conflicts is an important task of interdisciplinary research. The goals of research were achieved based on the analysis of social media data. Neural network modeling, statistical analysis, and differential equations were used as research methods. In mathematical modeling, three types of models were built: an equation of linear regression, as well as logistic and type-epidemiological mathematical models. The study showed that the use of parallel models using differential equations, mathematical statistics and neural network technology to determine the dynamics of aggressive online activity, in particular, to analyze users’ perception of conflict situations related to the topic of migrants, makes it possible to correctly analyze conflict zones in the development of a modern metropolis, to increase the effectiveness of research methods and predictive analytics of the development of social tension.

Concomitant excitation and tension development are required for myocellular gene expression and protein synthesis in rat skeletal muscle.

Loading-induced tension development is often assumed to constitute an independent cue to initiate muscle protein synthesis following resistance exercise. However, with traditional physiological models of resistance exercise, changes in loading-induced tension development also reflect changes in neural activation patterns, and direct evidence for a mechanosensitive mechanism is therefore limited. Here, we sought to examine the importance of excitation and tension development per se on initiation of signalling, gene transcription and protein synthesis in rat skeletal muscle. Isolated rat extensor digitorum longus muscles were allocated to the following interventions: (a) Excitation-induced eccentric contractions (ECC); (b) Passive stretching without excitation (PAS); (c) Excitation with inhibition of contractions (STIM+IMA ) and; (d) Excitation in combination with both inhibition of contractions and PAS (STIM+IMA +PAS). Assessment of transcriptional and translational signalling, gene transcription and acute muscle protein synthesis was compared in stimulated vs contra-lateral non-stimulated control muscle. Protein synthesis increased solely in muscles subjected to a combination of excitation and tension development (ECC and STIM+IMA +PAS). The same pattern was true for p38 mitogen-activated protein kinase signalling for gene transcription as well as for gene transcription of immediate early genes FOS and JUN. In contrast, mechanistic target of rapamycin Complex 1 signalling for translation initiation increased in all muscles subjected to increased tension development (ECC and STIM+IMA +PAS as well as PAS). The current study suggests that exercise-induced increases in protein synthesis as well as transcriptional signalling is dependent on the concomitant effect of excitation and tension development, whereas signalling for translation initiation is only dependent of tension development per se.

Suppression of myofilament cross-bridge kinetic in the heart of orchidectomized rats

AimsThe increased incidence of heart failure with reduced ejection fraction in men compared with women suggests that male sex hormones significantly impact myocardial contractile activation. This study aims to examine associations among molecular alterations, cellular modulations and in vivo cardiac contractile function upon deprivation of testicular hormones. Main methodsMyocardial structure and functions were compared among sham-operated control and twelve-week orchidectomized (ORX) male rats with and without testosterone supplementation. Key findingsEchocardiography and pressure-volume relationships demonstrated a decreased left ventricular ejection fraction compared with sham-operated controls. The percentage of contractility reduction was generally similar to the decrease in tension development detected in both right ventricular trabeculae and skinned isolated left ventricular cardiomyocytes of ORX rats. Reductions in tension cost and the rate constant of tension redevelopment (ktr) in ORX samples suggested a decrease in the rate of cross-bridge formation, reflecting a reduced number of cross-bridges. Slow cross-bridge detachment in ORX rat hearts could result from a shift of myosin heavy chain isoforms towards a slower ATPase activity β-isoform and reductions in the phosphorylation levels of cardiac troponin I and myosin binding protein-C. All the changes in the ORX rat heart, including ejection fractions and myofilament protein expression and phosphorylation, were completed attenuated by a physiological dose of testosterone. SignificanceTestosterone plays a critical role in regulating the mechanical and contractile dynamics of the heart. Deprivation of male sex hormones cause the loss of normal preserved cardiac contractile function leading to a high risk of severe cardiomyopathy progression.

Chenodeoxycholic and deoxycholic acids induced positive inotropic and negative chronotropic effects on rat heart.

Bile acids are endogenous amphiphilic steroids from the metabolites of cholesterol. Studies showed that they might contribute to the pathogenesis of cardiopathy in cholestatic liver diseases. Chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA) is associated with colon cancer, gallstones, and gastrointestinal disorders. However, little information is available regarding their cardiac effects. Here, we reported that CDCA (100μM) and DCA (100μM) significantly increased the left ventricular developed pressure of the isolated rat hearts to 122.3 ± 5.6% and 145.1 ± 13.7%, and the maximal rate of the pressure development rising and descending (± dP/dtmax) to 103.4 ± 17.6% and 124.4 ± 37.7% of the basal levels, respectively. They decreased the heart rate and prolonged the RR, QRS, and QT intervals of Langendorff-perfused hearts in a concentration-dependent manner. Moreover, CDCA and DCA increased the developed tension of left ventricular muscle and the cytosolic Ca2+ concentrations in left ventricular myocytes; these functions positively coordinated with their inotropic effects on hearts. Additionally, CDCA (150μM) and DCA (100μM) decreased the sinoatrial node beating rate to 80.6 ± 3.0% and 79.7 ± 0.9% of the basal rate (334.2 ± 10.7bpm), respectively. These results were consistent with their chronotropic effects. In conclusion, CDCA and DCA induced positive inotropic effects by elevating the Ca2+ in left ventricular myocytes. They exerted negative chronotropic effects by lowering the pace of the sinoatrial node in rat heart. These results indicated that the potential role of bile acids in cardiopathy related to cholestasis.

The use of Ca-transient to evaluate Ca2+ utilization by myofilaments in living cardiac muscle.

The kinetics of Ca2+ interaction with myofilaments is an important determinant of the preload-dependent effects on myocardial contractility (the Frank-Starling Mechanism). However, the direct evaluation of this interaction in intact tissue is limited. To overcome this issue, the method of difference curve was proposed, which implements the subtraction of the referent Ca-transient (measured in non-stretched muscle) from the Ca-transients measured at different preloads. This method was tested on the cardiac trabeculae of healthy (CONT) and monocrotaline-treated rats (MCT), subjected to force-length protocol with simultaneous measurement of isometric twitch and Ca-transient. The difference curve had two components, C2 and C3, which are distinct in their directions and, as hypothesized, may reflect mainly the kinetics of Ca2+ utilization by and release from myofilaments, respectively. Both the components were quantitatively evaluated by their amplitude, integral magnitude and time-to-peak. The C3 component in either CONT or MCT was significantly higher in its amplitude/integral magnitude vs the C2 component, at any preload (P<.05). The time-to-peak value was preload-dependent only for the C3 component. There were tight relationships between the above characteristics of C2/C3 components and the characteristics of isometric tension (peak value, time-to-peak and the maximal rates of rise/decline) in CONT and MCT muscles. The C3 component was highly consistent with tension relaxation (Ca2+ release from myofilaments), but the C2 component was partially consistent with tension development (Ca2+ utilization by myofilaments). The novel method of the analysis of Ca-transients can be utilized for indirect evaluation of Ca2+ interaction with myofilaments in healthy and diseased myocardium.

Immediate Effects of Median Nerve Mobilization on Nerve Conduction Velocities, Upperlimb Strength and Bimanual CoOrdination in Normal Healthy Subjects

Background and Objectives: - Neural tissue mobilization is a manipulative technique by which tissues are moved and stretched either by movement relative to surrounding structures or tension development. Mobilization of neural structures dependently or independently improves patient’s signs and symptoms. Nervous system adapts to lengthening through increase in intraneural or intramural pressures. Thus the continuum of the nervous system serve its ability to move either alone or through surrounding tissue interface to relieve contributing neural tension to patient’s symptoms. This Study assesses the immediate effects of neural tissue mobilization on the Nerve Conduction Velocities, the Bimanual Coordination and the Upper limb Grip Strength in normal healthy individuals. Materials and Method:- The participants in the study were normal healthy subjects. These subjects were assessed for their Upper limb Grip Strength, Bimanual coordination and the Nerve Conduction Velocities of the Median Nerve before and immediately after the Median Nerve Mobilization and analysis was done for the same. Result: - Data was analyzed by statistical means, standard deviation and students t- test and the results showed significant changes in terms of the nerve conduction velocity, upper limb strength and bimanual co-ordination in normal healthy subjects on an immediate basis. Conclusion: - This study concludes that immediate effects of median nerve mobilization on Nerve Conduction Velocities, Bimanual Coordination and Upper Limb Strength in normal healthy subjects are statisticaly significant. Hence immediate relief of discomfort through neural mobilization on these parameters can be obtained.

Elements of Technology for Producing Cold-Formed Rebar from C86D Steel Using an Idle Stand

For the production of high-strength reinforcing bars with a diameter of 9.5 mm from C86D steel, cold-formed rebar with a diameter of 9.7 mm was used, made according to the direct drawing scheme from hot-rolled coiled steel with a diameter of 16.0 mm, which was subjected to cold profiling with a dent depth of 0.20 mm in an idle three-roller stand and subsequent stabilization at a temperature of 390 ± 10°C with a specific technological tension of 480 MPa. The power parameters of the application of a periodic profile on the conversion workpiece, the maximum value of the forces acting on the rollers, as well as the values of the required pulling force, have been determined. It has been experimentally shown that a 5.0% decrease in the idle cross-section of a reinforcing bar after deposition of indentations and stabilization is compensated by an increase in σu and σ0.2 by 4.6 and 8.7%, respectively. It has been shown that correction of roll adjustment is necessary during the line riding period and development of process tension. The proposed methodological approach with the use of modeling makes it possible to design equipment for the profiling of rebar integrated into the line of the stabilization section with a pulling device.

Foot stiffening during the push-off phase of human walking is linked to active muscle contraction, and not the windlass mechanism.

The rigidity of the human foot is often described as a feature of our evolution for upright walking and is bolstered by a thick plantar aponeurosis that connects the heel to the toes. Previous descriptions of human foot function consider stretch of the plantar aponeurosis via toe extension (windlass mechanism) to stiffen the foot as it is levered against the ground for push-off during walking. In this study, we applied controlled loading to human feet in vivo, and studied foot function during the push-off phase of walking, with the aim of carefully testing how the foot is tensioned during contact with the ground. Both experimental paradigms revealed that plantar aponeurosis strain via the 'windlass mechanism' could not explain the tensioning and stiffening of the foot that is observed with increased foot-ground contact forces and push-off effort. Instead, electromyographic recordings suggested that active contractions of ankle plantar flexors provide the source of tension in the plantar aponeurosis. Furthermore, plantar intrinsic foot muscles were also contributing to the developed tension along the plantar aspect of the foot. We conclude that active muscular contraction, not the passive windlass mechanism, is the foot's primary source of rigidity for push-off against the ground during bipedal walking.

Adjustments in β-Adrenergic Signaling Contribute to the Amelioration of Cardiac Dysfunction by Exercise Training in Supravalvular Aortic Stenosis.

Aortic stenosis-induced chronic pressure overload leads to cardiac dysfunction and congestive heart failure. The pathophysiological mechanisms of the myocardial impairment are multifactorial and include maladaptive β-adrenergic signaling. Exercise training (ET) has been used as a non-pharmacological therapy for heart failure management. The present study tested the hypothesis that exercise training attenuates diastolic dysfunction through β-adrenergic signaling preservation. Wistar rats were submitted to ascending aortic stenosis (AS) surgery, and after 18 weeks, a moderate aerobic exercise training protocol was performed for ten weeks. ET attenuated diastolic dysfunction, evaluated by echocardiogram and isolated papillary muscle (IPM) assay. Also, ET reduced features of heart failure, cross-sectional cardiomyocyte area, and exercise intolerance, assessed by treadmill exercise testing. The β2 adrenergic receptor protein expression was increased in AS rats independently of exercise. Interestingly, ET restored the protein levels of phosphorylated phospholamban at Serine 16 and preserved the β-adrenergic receptor responsiveness as visualized by the lower myocardial compliance decline and time to 50% tension development and relaxation during β-adrenergic stimulation in the IPM than untrained rats. Additionally, AS rats presented higher levels of TNFα and iNOS, which were attenuated by ET. Moderate ET improves exercise tolerance, reduces heart failure features, and attenuates diastolic dysfunction. In the myocardium, ET decreases the cross-sectional area of the cardiomyocyte and preserves the β-adrenergic responsiveness, which reveals that the adjustments in β-adrenergic signaling contribute to the amelioration of cardiac dysfunction by mild exercise training in aortic stenosis rats.

Acute chloroquine poisoning: A comprehensive experimental toxicology assessment of the role of diazepam

Background and PurposeResurgence in the use of chloroquine as a potential treatment for COVID‐19 has seen recent cases of fatal toxicity due to unintentional overdoses. Protocols for the management of poisoning recommend diazepam, although there are uncertainties in its pharmacology and efficacy in this context. The aim was to assess the effects of diazepam in experimental models of chloroquine cardiotoxicity.Experimental ApproachIn vitro experiments involved cardiac tissues isolated from rats and incubated with chloroquine alone or in combination with diazepam. In vivo models of toxicity involved chloroquine administered intravenously to pentobarbitone‐anaesthetised rats and rabbits. Randomised, controlled treatment studies in rats assessed diazepam, clonazepam and Ro5‐4864 administered: (i) prior, (ii) during and (iii) after chloroquine and the effects of diazepam: (iv) at high dose, (v) in urethane‐anaesthetised rats and (vi) co‐administered with adrenaline.Key ResultsChloroquine decreased the developed tension of left atria, prolonged the effective refractory period of atria, ventricular tissue and right papillary muscles, and caused dose‐dependent impairment of haemodynamic and electrocardiographic parameters. Cardiac arrhythmias indicated impairment of atrioventricular conduction. Studies (i), (ii) and (v) showed no differences between treatments and control. Diazepam increased heart rate in study (iv) and as with clonazepam also prolonged the QTc interval in study (iii). Combined administration of diazepam and adrenaline in study (vi) improved cardiac contractility but caused hypokalaemia.Conclusion and ImplicationsNeither diazepam nor other ligands for benzodiazepine binding sites protect against or attenuate chloroquine cardiotoxicity. However, diazepam may augment the effects of positive inotropes in reducing chloroquine cardiotoxicity.Linked ArticlesThis article is part of a themed issue on The Pharmacology of COVID‐19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc

Tensions in future development of organic production\u2014views of stakeholders on Organic 3.0

This study analysed Swedish stakeholders’ views on future developments of organic production and consumption based on Organic 3.0, a strategic initiative by the International Federation of Organic Agriculture Movements (IFOAM). Focus group discussions were carried out with actors representing different parts of the organic value chain in Sweden. These identified a number of tensions, four of which represented an unresolved dichotomy in the way forward for the organic movement and its relevance for organic production in most settings. The first tension was between the drive for increased efficiency to achieve higher yields and an agroecological approach with broader sustainability values. The second concerned availability of plant nutrients in organic agriculture including safe recirculating of nutrients from society. The third tension set new technology against the precautionary principle and the notion of naturalness. The fourth concerned the role of organic as an innovation system; whether organic should be a forerunner, i.e. performing well above average and fostering innovation, or whether organic should be a broader movement including more farmers but then requiring more regulations that may hinder innovation. These tensions will result in important choices on direction for the organic sector as it pursues the Organic 3.0 goal of sustainably feeding a growing population based on farming systems based on organic principles.

Exploring the Factors Contributing to the High Ultimate pH of Broiler Pectoralis Major Muscles Affected by Wooden Breast Condition.

The elevated ultimate pH (pHu) found in wooden breast (WB) meat suggests an altered muscular energetic status in WB but also could be related to a prematurely terminated post-mortem pH decline. The aims of this study were to explore the factors contributing to the elevated pHu and establish whether the occurrence of WB defect alters muscle post-mortem carbohydrate metabolism and determine if the contractile apparatus reflects such changes. A total of 24 carcasses from Ross 308 male chickens were obtained from a commercial producer and harvested using commercial processing procedures. Carcasses were categorized into unaffected (NORM) and WB groups (n = 12 each), and samples were collected from cranial bone-in pectoralis major (PM) muscles at 15 min and 24 h post-mortem for the determination of pH, glycolytic metabolites, adenonucleotides, buffering capacity, phosphofructokinase (PFK) activity, and in vitro pH decline. Twenty-four additional deboned PM samples (12 NORM and 12 WB) were collected from the same processing plant to assess muscle histology and sarcomere length at four different locations throughout the PM muscle. Data show that the reduced glycolytic potential of WB muscles only partially explains the higher (P < 0.001) pHu of WB meat, as residual glycogen along with unaltered PFK activity suggests that neither glycogen nor a deficiency of PFK is responsible for arresting glycolysis prematurely. The dramatic reduction in ATP concentrations in the early post-mortem period suggests a defective ATP-generating pathway that might be responsible for the reduced pH decline in WB samples. Further, the addition of excess of ATPase extended post-mortem glycolysis of WB meat in an in vitro glycolytic system. WB-affected samples have longer (P < 0.001) sarcomeres compared to NORM, indicating the existence of compromised energy-generating pathways in myopathic muscles that may have had consequences on the muscle contraction and tension development, as in vivo, also during the post-mortem period. Considering the overall reduced glycolytic potential and the myodegenerative processes associated with WB condition, we speculate that the higher pHu of WB meat might be the outcome of a drastically impaired energy-generating pathway combined with a deficiency and/or a dysfunction of muscle ATPases, having consequences also on muscle fiber contraction degree.

AT1Receptor Blockade Improves Myocardial Functional Performance in Obesity.

ResumoFundamento A obesidade tem sido associada com ativação crônica do sistema renina-angiotensina-aldosterona e importantes alterações no desempenho cardíaco.Objetivo Avaliar a influência do bloqueio de receptores de angiotensina-II do tipo 1 (AT1) sobre a morfologia e desempenho cardíaco de ratos obesos por dietaMétodos Ratos Wistar (n=48) foram submetidos a dieta controle (2,9 kcal/g) ou hiperlipídica (3,6 kcal/g) durante 20 semanas. Após a 16ª semana, foram distribuídos em quatro grupos: Controle (CO), Obeso (OB), Controle Losartan (CL) e Obeso Losartan (OL). CL e OL receberam losartan (30 mg/kg/dia) na água durante quatro semanas. Posteriormente, foram analisadas composição corporal, pressão arterial sistólica (PAS) e ecocardiograma. A função de músculos papilares foi avaliada em situação basal com concentração de cálcio ([Ca2+]o) de 2,50 mM e após manobras inotrópicas: potencial pós-pausa (PPP), elevação da [Ca2+]o e durante estimulação beta-adrenérgica com isoproterenol. A análise dos resultados foi feita por meio de Two-Way ANOVA e teste de comparações apropriado. O nível de significância considerado foi de 5%.Resultados Embora a alteração da PAS não tenha se mantido ao final do experimento, a obesidade se associou com hipertrofia cardíaca e maior velocidade de encurtamento da parede posterior do ventrículo esquerdo.No estudo de músculos papilares em condição basal, CL mostrou menor velocidade máxima de variação negativa da tensão desenvolvida (-dT/dt) do que CO. O PPP de 60s promoveu menor -dT/dt e pico de tensão desenvolvida (TD) em OB e CL, comparados ao CO, e maior variação relativa de TD e velocidade máxima de variação positiva (+dT/dt) no OL em relação a CL e OB. Sob 1,5, 2,0 e 2,5mM de [Ca2+]o, o grupo OL exibiu maior -dT/dt do que CL.Conclusão Losartan melhora a função miocárdica de ratos com obesidade induzida por dieta. (Arq Bras Cardiol. 2020; 115(1):17-28)

Travels with Jack

Nonprofit arts organization the ZBS Foundation began as a “media commune” in the early 1970s and continues to the present day: a period that spans dramatic changes in American radio culture and audio technology. The key creative figure at ZBS is the writer and producer Thomas Lopez, whose work serves as a case study in a “post-network” style of radio drama, one shaped by multitrack editing, field recording, and the ethos of the 1960s counterculture. The ZBS aesthetic comes into sharpest focus in the Jack Flanders adventure series, which demonstrates how ZBS adapted a “theater of the mind” approach to radio drama to create a “theater of the mind-body” that re-accentuated earlier conventions of the radio adventure serial for a countercultural audience. Lopez’s increasing use of field recordings to structure his narratives established a formal tension between the inner exploration of the hero’s psyche and an encounter with different cultures. I chart the development of this formal tension in ZBS’s theater of the mind-body and argue that Lopez’s work with ZBS is a bridge across multiple eras of radio, an archive of enduring characters and distinctive styles of storytelling, and a sonic laboratory for the fostering of cultural dialogue through sound.

Effects of fasting on isolated murine skeletal muscle contractile function during acute hypoxia.

Stored muscle carbohydrate supply and energetic efficiency constrain muscle functional capacity during exercise and are influenced by common physiological variables (e.g. age, diet, and physical activity level). Whether these constraints affect overall functional capacity or the timing of muscle energetic failure during acute hypoxia is not known. We interrogated skeletal muscle contractile properties in two anatomically distinct rodent hindlimb muscles that have well characterized differences in energetic efficiency (locomotory- extensor digitorum longus (EDL) and postural- soleus muscles) following a 24 hour fasting period that resulted in substantially reduced muscle carbohydrate supply. 180 mins of acute hypoxia resulted in complete energetic failure in all muscles tested, indicated by: loss of force production, substantial reductions in total adenosine nucleotide pool intermediates, and increased adenosine nucleotide degradation product-inosine monophosphate (IMP). These changes occurred in the absence of apparent myofiber structural damage assessed histologically by both transverse section and whole mount. Fasting and the associated reduction of the available intracellular carbohydrate pool (~50% decrease in skeletal muscle) did not significantly alter the timing to muscle functional impairment or affect the overall force/work capacities of either muscle type. Fasting resulted in greater passive tension development in both muscle types, which may have implications for the design of pre-clinical studies involving optimal timing of reperfusion or administration of precision therapeutics.

Altered Sarcomeric Structure and Function in Woody Breast Myopathy of Avian Pectoralis Major Muscle.

The “Woody” or “Wooden” breast disease is a severe myopathy of pectoralis major muscle recently identified within rapidly growing broiler lines all around the world with a prevalence rate around 20%, or even higher. Although of significant ethical and economic impact, little is known regarding the structural and functional aspects of the contractile apparatus in the woody breast muscle. The aim of the present study was to determine physiological properties of the contractile system in the morphologically intact muscle fibers of focally damaged woody breast in comparison with normal muscle fibers to gain insight into the muscle function of the animal and possibly mechanisms involved in the disease development. Muscle samples were taken from woody breast (non-lesioned areas) and normal breast muscles from broilers. Length-tension curves, maximal active stress, maximal shortening velocity, calcium sensitivity, rate of tension development, lattice spacing and muscle biochemical composition were investigated on single skinned fibers. Sarcomeres of woody breast fibers were more compliant, which is very likely related to the wider spacing (18% wider compared to controls) between thick and thin filament. No differences were found in optimal sarcomere length (2.68 ± 0.04 vs. 2.65 ± 0.05 μm) nor in maximal active stress (116 ± 17 vs. 125 ± 19 mN mm–2). However, woody breast fibers had less steep descending arm as shown in length-tension curve. Woody breast muscle fibers had 40% bigger sarcomeric volume compared to controls. Content of contractile proteins (myosin and actin), and maximal shortening velocity were unchanged indicating that the growth in woody breast muscle fiber was associated with synthesis of new contractile units with unaltered kinetics. Calcium sensitivity was decreased in woody breast muscle fibers significantly. In conclusion, the results show that the rapid growth of muscle in woody breast disease is associated with significant structural and functional changes in the pectoralis major musculature, associated with alterations in the mechanical anchoring of contractile filaments.

Differential Mesenteric Venous and Arterial Vascular Reactivity to Adenosine between Rats, Dogs, Mini‐pigs, and Human

It is well established that adenosine induces arterial vasodilation in various vascular beds. However, its effect on the venous circulation is still largely unknown. The splanchnic system receives approximately 25% of cardiac output (CO) and contains approximately 20% of total blood volume. Mesenteric (part of splanchnic system, o. d. 150–250 μm) arteries (MA) and their adjacent veins (MV) from rats, dogs, mini‐pigs and humans were isolated and mounted on a myograph (DMT Technology, USA). Vessels were preconstricted with 1 μM phenylephrine (PE) for arteries and prostaglandin F2α (PGF2α) for veins. Cumulative concentrations of 5’‐N‐Ethylcarboxamidoadenosine (NECA, 10−11 – 10−5 M), a non‐specific adenosine agonist, were applied and evaluated. Tension development was normalized to the tension induced by PE/PGF2α as %. NECA induced a concentration dependent arterial vasodilation in all 3 animals and human MA (Fig. 1). The effects were very similar in all 3 animals (maximum of 91.09±10.94% to 93.88±1.93%), however human responses were less pronounced (maximum of 59.14±4.61%). Interestingly, veins from all species responded to NECA very differently (Fig. 2). MVs from rats were the only vessels that constricted strongly in response to NECA (182.94±17.52% of pre‐constriction), which has not been previously reported (Figs. 2– 3). NECA induced vasodilation in MV from the other species varied. NECA induced vasodilation in MV from dogs were similar to MA at high concentrations (Fig. 6, 10−8 M and above). However, MV from mini‐pig (Fig. 5) and human (Fig. 6) responses were minimal (Fig. 2, maximum of 24.56±14.67% in mini‐pig and 33.54±9.61% relaxation in human) compared to 92.93±2.26% relaxation in dogs. In conclusion, although mesenteric arterial vascular reactivity responds similarly to adenosine among species, mesenteric venous vascular reactivity responses varied greatly to adenosine among species. MVs from rats were the only vessel constricted strongly in response to NECA. Caution is advised when choosing animal models for studying vascular reactivity.Figure 1Figure 2Figure 3Figure 4Figure 5Figure 6