Small Amounts of α-Myosin Heavy Chain Isoform Expression Significantly Increase Power Output of Rat Cardiac Myocyte Fragments

The publisher's version of this article may be found at http://circres.ahajournals.org/cgi/content/abstract/90/11/1150?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&searchid=1049671889562_931&stored_search=&FIRSTINDEX=0&volume=90&firstpage=1150&search_url=http%3A%2F%2Fcircres.ahajournals.org%2Fcgi%2Fsearch&journalMyocardial performance is likely affected by the relative expression of the two myosin heavy chain (MyHC) isoforms, namely {alpha}-MyHC and ß-MyHC. The relative expression of each isoform is regulated developmentally and in pathophysiological states. Many pathophysiological states are associated with small shifts in the relative expression of each MyHC isoform, yet the functional consequence of these shifts remains unclear. The purpose of this study was to determine the functional effect of a small shift in the relative expression of {alpha}-MyHC. To this end, power output was measured in rat cardiac myocyte fragments that expressed {approx}12% {alpha}-MyHC and in myocyte fragments that expressed {approx}0% {alpha}-MyHC, as determined in the same cells by SDS-PAGE analysis after mechanical experiments. Myocyte fragments expressing {approx}12% {alpha}-MyHC developed {approx}52% greater peak normalized power output than myocyte fragments expressing {approx}0% {alpha}-MyHC. These results indicate that small amounts of {alpha}-MyHC expression significantly augment myocyte power output.This work was supported by National Heart, Lung, and Blood Institute Grant HL-57852 (K.S.M.) and a predoctoral fellowship granted by the Heartland Affiliate of the American Heart Association (T.J.H.)

Power Output Is Increased After Phosphorylation of Myofibrillar Proteins in Rat Skinned Cardiac Myocytes

This work was supported by American Heart Association Beginning Grant-in-Aid 9914291 and NIH Grant HL57852.The publisher's version may be found at http://circres.ahajournals.org/cgi/content/full/89/12/1184ß-Adrenergic stimulation increases stroke volume in mammalian hearts as a result of protein kinase A (PKA)-induced phosphorylation of several myocyte proteins. This study investigated whether PKA-induced phosphorylation of myofibrillar proteins directly affects myocyte contractility. To test this possibility, we compared isometric force, loaded shortening velocity, and power output in skinned rat cardiac myocytes before and after treatment with the catalytic subunit of PKA. Consistent with previous studies, PKA increased phosphorylation levels of myosin binding protein C and troponin I, and reduced Ca2+ sensitivity of force. PKA also significantly increased both maximal force (25.4±8.3 versus 31.6±11.3 µN [P<0.001, n=12]) and peak absolute power output (2.48±1.33 versus 3.38±1.52 µW/mg [P<0.05, n=5]) during maximal Ca2+ activations. Furthermore, PKA elevated power output at nearly all loads even after normalizing for the increase in force. After PKA treatment, peak normalized power output increased {approx}20% during maximal Ca2+ activations (n=5) and {approx}33% during half-maximal Ca2+ activations (n=9). These results indicate that PKA-induced phosphorylation of myofibrillar proteins increases the power output-generating capacity of skinned cardiac myocytes, in part, by speeding the step(s) in the crossbridge cycle that limit loaded shortening rates, and these changes likely contribute to greater contractility in hearts after ß-adrenergic stimulation

Effect of Training Mode on Post-Exercise Heart Rate Recovery of Trained Cyclists

The sympathetic nervous system dominates the regulation of body functions during exercise. Therefore after exercise, the sympathetic nervous system withdraws and the parasympathetic nervous system helps the body return to a resting state. In the examination of this relationship, the purpose of this study was to compare recovery heart rates (HR) of anaerobically versus aerobically trained cyclists. With all values given as means ± SD, anaerobically trained track cyclists (n=10, age=25.9 ± 6.0 yrs, body mass=82.7 ± 7.1 kg, body fat=10.0 ± 6.3%) and aerobically trained road cyclists (n=15, age=39.9 ± 8.5 yrs, body mass=75.3 ± 9.9 kg, body fat=13.1 ± 4.5%) underwent a maximal oxygen uptake test. Heart rate recovery was examined on a relative basis using heart rate reserve as well as the absolute difference between maximum HR and each of two recovery HRs. The post-exercise change in HR at minute one for the track cyclists and road cyclists respectively were 22 ± 8 bpm and 25 ± 12 bpm. At minute two, the mean drop for track cyclists was significantly (p\u3c0.05) greater than the road cyclists (52 ± 15 bpm and 64 ± 11 bpm). Training mode showed statistically significant effects on the speed of heart rate recovery in trained cyclists. Greater variability in recovery heart rate at minute two versus minute one suggests that the heart rate should be monitored longer than one minute of recovery for a better analysis of post-exercise autonomic shif

Exploitation and Detection of a Malicious Mobile Application

Mobile devices are increasingly being embraced by both organizations and individuals in today’s society. Specifically, Android devices have been the prominent mobile device OS for several years. This continued amalgamation creates an environment that is an attractive attack target. The heightened integration of these devices prompts an investigation into the viability of maintaining non-compromised devices. Hence, this research presents a preliminary investigation into the effectiveness of current commercial anti-virus, static code analysis and dynamic code analysis engines in detecting unknown repackaged malware piggybacking on popular applications with excessive permissions. The contribution of this paper is two-fold. First, it provides an initial assessment of the effectiveness of anti-virus and analysis tools in detecting malicious applications and behavior in Android devices. Secondly, it provides process for inserting code injection attacks to stimulate a zero-day repackaged malware that can be used in future research efforts

Detecting Repackaged Android Applications Using Perceptual Hashing

The last decade has shown a steady rate of Android device dominance in market share and the emergence of hundreds of thousands of apps available to the public. Because of the ease of reverse engineering Android applications, repackaged malicious apps that clone existing code have become a severe problem in the marketplace. This research proposes a novel repackaged detection system based on perceptual hashes of vetted Android apps and their associated dynamic user interface (UI) behavior. Results show that an average hash approach produces 88% accuracy (indicating low false negative and false positive rates) in a sample set of 4878 Android apps, including 2151 repackaged apps. The approach is the first dynamic method proposed in the research community using image-based hashing techniques with reasonable performance to other known dynamic approaches and the possibility for practical implementation at scale for new applications entering the Android market

Design of Vitrification Machine

Cryopreservation of living cells and biological material by vitrification requires the expertise of a skilled lab technician and a large amount of time. Vitrification must be performed one sample at a time on tiny subjects, which makes for a tedious and unreliable process. Moreover, there is a lack of standardization in the methods for preparing cells and biological material for the vitrification process. The purpose of the Vitrification Machine is to greatly simplify the process by making it faster, more efficient, cheaper and more reliable. The machine will be capable of handling several subjects at a time and will completely automate the most tedious portions of the vitrification process. This ease of use will allow researchers to experiment with new vitrification preparation methods on a larger number of samples more quickly and reliably. The applications of the Vitrification Machine are wide, but it is specifically being developed to automate the vitrification of human oocytes and eventually embryos. Female patients diagnosed with diseases whose treatments are detrimental to the reproductive process (such as chemotherapy), can have their oocytes preserved for use after their treatment is complete. The automation of vitrification by the Vitrification Machine will make this process faster, more reliable, more affordable, and therefore more available to patients. There currently is no known product on the market that fills all these needs or has the potential to drive down the cost of this portion of the fertility preservation process. Since the Vitrification Machine will be useful to clinical In-Vitro Fertilization (IVF) laboratories, animal science research and fertility specialists in both research and clinical settings, the market potential of the product is very large

An evaluation of sexual dimorphism in head size and shape of Red Salamanders (Pseudotriton ruber)

For many secretive species of amphibians and reptiles, observations of reproductive behavior are limited to sparse anecdotes from the field or to animals held in captivity. However, a careful examination of morphological differences between the sexes can help shape hypotheses about behaviors with which they may be correlated. For example, sexual dimorphism in head size and shape are correlated with courtship, territoriality, and mate-defense behaviors in some salamanders. One widespread species with a poorly described reproductive natural history is the Red Salamander (Pseudotriton ruber). Here, we measure head size and employ geometric morphometric methods to evaluate head shape in P. ruber, with the goals of: 1) quantifying and visualizing sexual variation; 2) forming hypotheses about reproductive behavior. We found preliminary evidence for differences in head size and shape that are consistent with mate-guarding behavior, and we remark upon directions for future research