From Betrayal to Power

Resistance is the secret of joy! --Alice Walker Possessing the Secret of Joy What does it mean to love a daughter in a culture that is hostile to her integrity? In a culture where power equals dominance and superiority, men\u27s control of public life--the world of political and economic power that shapes the desires of private life--places mothers in a double bind as their daughters approach womanhood. The common ways that mothers have of guiding daughters--what we call the paths of least resistance in chapter two 1 --ask girls to make deep psychological sacrifices to straddle the cultural division of work, in the male public world of politics and business, and love, in the female private world of home and family. As girls find that they cannot enter patriarchy fully and powerfully as themselves, they feel betrayed by their mothers. But mothers did not create the separate spheres of public and private life. It is this cultural betrayal of human integrity, which divides our wholeness into these separate spheres, that makes loving and raising a daughter political work. The romance-into-mothering myth created in the mid-1800s told women that their true nature is best expressed in the home, in private life. 2 When market-driven factory life in the Industrial Revolution consumed women\u27s traditional work of producing food, clothing, medicine, and crafts, women were suddenly stripped of their expertise and authority. Rather than adopting a rationalist solution of admitting women into modern society ..

Potential molecular mechanisms underlying muscle fatigue mediated by reactive oxygen and nitrogen species

Intense contractile activity causes a dramatic decline in the force and velocity generating capacity of skeletal muscle within a few minutes, a phenomenon that characterizes fatigue. Much of the research effort has focused on how elevated levels of the metabolites of ATP hydrolysis might inhibit the function of the contractile proteins. However there is now growing evidence that elevated levels of reactive oxygen and nitrogen species (ROS/RNS), which also accumulate in the myoplasm during fatigue, also play a causative role in this type of fatigue. The most compelling evidence comes from observations demonstrating that pre-treatment of intact muscle with a ROS scavenger can significantly attenuate the development of fatigue. A clear advantage of this line of inquiry is that the molecular targets and protein modifications of some of the ROS scavengers are well-characterized enabling researchers to begin to identify potential regions and even specific amino acid residues modified during fatigue. Combining this knowledge with assessments of contractile properties from the whole muscle level down to the dynamic motions within specific contractile proteins enable the linking of the structural modifications to the functional impacts, using advanced chemical and biophysical techniques. Based on this approach at least two areas are beginning emerge as potentially important sites, the regulatory protein troponin and the actin binding region of myosin. This review highlights some of these recent efforts which have the potential to offer uniquely precise information on the underlying molecular basis of fatigue. This work may also have implications beyond muscle fatigue as ROS/RNS mediated protein modifications are also thought to play a role in the loss of muscle function with aging and in some acute pathologies like cardiac arrest and ischemia

Muscle Fatigue from the Perspective of a Single Crossbridge

The repeated intense stimulation of skeletal muscle rapidly decreases its force- and motion-generating capacity. This type of fatigue can be temporally correlated with the accumulation of metabolic by-products, including phosphate (Pi) and protons (H+). Experiments on skinned single muscle fibers demonstrate that elevated concentrations of these ions can reduce maximal isometric force, unloaded shortening velocity, and peak power, providing strong evidence for a causative role in the fatigue process. This seems to be due, in part, to their direct effect on muscle’s molecular motor, myosin, because in assays using isolated proteins, these ions directly inhibit myosin’s ability to move actin. Indeed, recent work using a single molecule laser trap assay has revealed the specific steps in the crossbridge cycle affected by these ions. In addition to their direct effects, these ions also indirectly affect myosin by decreasing the sensitivity of the myofilaments to calcium, primarily by altering the ability of the muscle regulatory proteins, troponin and tropomyosin, to govern myosin binding to actin. This effect seems to be partially due to fatigue-dependent alterations in the structure and function of specific subunits of troponin. Parallel efforts to understand the molecular basis of muscle contraction are providing new technological approaches that will allow us to gain unprecedented molecular detail of the fatigue process. This will be crucial to fully understand this ubiquitous phenomenon and develop appropriately targeted therapies to attenuate the debilitating effects of fatigue in clinical populations

Low Cell pH Depresses Peak Power in Rat Skeletal Muscle Fibres at Both 30°C and 15°C: Implications for Muscle Fatigue

Historically, an increase in intracellular H+ (decrease in cell pH) was thought to contribute to muscle fatigue by direct inhibition of the cross-bridge leading to a reduction in velocity and force. More recently, due to the observation that the effects were less at temperatures closer to those observed in vivo, the importance of H+ as a fatigue agent has been questioned. The purpose of this work was to re-evaluate the role of H+ in muscle fatigue by studying the effect of low pH (6.2) on force, velocity and peak power in rat fast-and slow-twitch muscle fibres at 15°C and 30°C. Skinned fast type IIa and slow type I fibres were prepared from the gastrocnemius and soleus, respectively, mounted between a force transducer and position motor, and studied at 15°C and 30°C and pH 7.0 and 6.2, and fibre force (P0), unloaded shortening velocity (V0), force–velocity, and force–power relationships determined. Consistent with previous observations, low pH depressed the P0 of both fast and slow fibres, less at 30°C (4–12%) than at 15°C (30%). However, the low pH-induced depressions in slow type I fibre V0 and peak power were both significantly greater at 30°C (25% versus 9% for V0 and 34% versus 17% for peak power). For the fast type IIa fibre type, the inhibitory effect of low pH on V0 was unaltered by temperature, while for peak power the inhibition was reduced at 30°C (37% versus 18%). The curvature of the force–velocity relationship was temperature sensitive, and showed a higher a/P0 ratio (less curvature) at 30°C. Importantly, at 30°C low pH significantly depressed the ratio of the slow type I fibre, leading to less force and velocity at peak power. These data demonstrate that the direct effect of low pH on peak power in both slow-and fast-twitch fibres at near-in vivo temperatures (30°C) is greater than would be predicted based on changes in P0, and that the fatigue-inducing effects of low pH on cross-bridge function are still substantial and important at temperatures approaching those observed in vivo

High Rate Discharge Studies of LI/SO2 Batteries

A battery composed of twelve lithium/sulfur dioxide D size cells in series is forced discharged at 21 amperes. This current is established by the proposed use of the battery and represented a discharge condition which might produce venting. Discharge of the battery into voltage reversal results not only in cells venting but also in the violent rupture of at least one cell

Determining the influence and effects of manufacturing variables on sulfur dioxide cells

A survey of the Li/SO2 manufacturing community was conducted to determine where variability exists in processing. The upper and lower limits of these processing variables might, by themselves or by interacting with other variables, influence safety, performance, and reliability. A number of important variables were identified and a comprehensive design experiment is being proposed to make the proper determinations

Atrial natriuretic factor

The discovery of the first well-defined natriuretic hormone, the Atrial Natriuretic Factor (ANF), has prompted research on its impact on volume regulation in health and disease. The natriuretic, diuretic, and smooth muscle-relaxing properties suggest an important role of this novel hormone in pathophysiological states with sodium or volume retention, such as congestive heart failure or cirrhosis of the liver. Investigations on the implications of ANF in liver disease have been performed for little more than 1 year, and results are still controversial in many respects. At present, it seems very likely that there is no absolute deficiency of plasma ANF in patients with cirrhosis. Moreover, elevated plasma levels in cirrhotics with ascites have been reported by several groups. However, as yet, a molecular characterization of this increased immunoreactivity is still lacking. There is disagreement on the reduced release of and renal response to ANF in subgroups of cirrhotics; however, stimulus-response-coupling might be impaired. Further studies are needed to elucidate the pathophysiological implications and therapeutical potential of ANF in patients with chronic liver disease

LAMINAR SMOKE POINTS OF COFLOWING DIFFUSION FLAMES IN MICROGRAVITY

Nonbuoyant laminar jet diffusion flames in coflowing air were observed aboard the International Space Station with an emphasis on laminar smoke points. The tests extended the 2009 Smoke Points In Coflow Experiment (SPICE) experiment to new fuels and burner diameters. Smoke points were found for methane, ethane, ethylene, and propane burning in air. Conditions included burner diameters of 0.76, 1.6, 2.1, and 3.2 mm and coflow velocities of 3.0 - 47 cm/s. This study yielded 57 new smoke points to increase the total number of smoke points observed to 112. Smoke point lengths were found to scale with burner diameter raised to the -0.67 power times coflow velocity raised to the 0.27 power. Sooting propensity was observed to rank according to methane < ethane < ethylene < propane < 50% propylene < 75% propylene < propylene. This agrees with past normal gravity measurements except for the exchanged positions of ethylene and propane. This is the first time a laminar smoke point has been observed for methane at atmospheric pressure

The likely effects of thermal climate change on vertebrate skeletal muscle mechanics with possible consequences for animal movement and behaviour

Climate change can involve alteration in the local temperature that an animal is exposed to, which in turn may affect skeletal muscle temperature. The underlying effects of temperature on the mechanical performance of skeletal muscle can affect organismal performance in key activities, such as locomotion and fitness-related behaviours, including prey capture and predator avoidance. The contractile performance of skeletal muscle is optimized within a specific thermal range. An increased muscle temperature can initially cause substantial improvements in force production, faster rates of force generation, relaxation, shortening, and production of power output. However, if muscle temperature becomes too high, then maximal force production and power output can decrease. Any deleterious effects of temperature change on muscle mechanics could be exacerbated by other climatic changes, such as drought, altered water, or airflow regimes that affect the environment the animal needs to move through. Many species will change their location on a daily, or even seasonal basis, to modulate the temperature that they are exposed to, thereby improving the mechanical performance of their muscle. Some species undergo seasonal acclimation to optimize muscle mechanics to longer-term changes in temperature or undergo dormancy to avoid extreme climatic conditions. As local climate alters, species either cope with the change, adapt, avoid extreme climate, move, or undergo localized extinction events. Given that such outcomes will be determined by organismal performance within the thermal environment, the effects of climate change on muscle mechanics could have a major impact on the ability of a population to survive in a particular location

Have cochlear implant, won’t have to travel: introducing telemedicine to people using cochlear implants

Purpose: This paper describes a planned project to design, implement, and evaluate remote care for adults using cochlear implants and compare their outcomes with those following the standard care pathway.Method: Sixty people with cochlear implants will be recruited and randomized to either the remote care group or a control group. The remote care group will use new tools for 6 months: remote and self-monitoring, self-adjustment of device, and a personalized online support tool. The main outcome measure is patient empowerment, with secondary outcomes of hearing and quality of life stability, patient and clinician preference, and use of clinic resources.Conclusion: The clinical trial ends in summer 2016. Remote care may offer a viable method of follow-up for some adults with cochlear implants