Nitric oxide suppresses cerebral vasomotion by sGC-independent effects on ryanodine receptors and voltage-gated calcium channels

Background/Aims: In cerebral arteries, nitric oxide (NO) release plays a key role in suppressing vasomotion. Our aim was to establish the pathways affected by NO in rat middle cerebral arteries. Methods: In isolated segments of artery, isometric tension and simultaneous measurements of either smooth muscle membrane potential or intracellular [Ca 2+ ] ([Ca 2+ ] SMC ) changes were recorded. Results: In the absence of L -NAME, asynchronous propagating Ca 2+ waves were recorded that were sensitive to block with ryanodine, but not nifedipine. L -NAME stimulated pronounced vasomotion and synchronous Ca 2+ oscillations with close temporal coupling between membrane potential, tone and [Ca 2+ ] SMC . If nifedipine was applied together with L -NAME, [Ca 2+ ] SMC decreased and synchronous Ca 2+ oscillations were lost, but asynchronous propagating Ca 2+ waves persisted. Vasomotion was similarly evoked by either iberiotoxin, or by ryanodine, and to a lesser extent by ODQ. Exogenous application of NONOate stimulated endothelium-independent hyperpolarization and relaxation of either L -NAME-induced or spontaneous arterial tone. NO-evoked hyperpolarization involved activation of BK Ca channels via ryanodine receptors (RYRs), with little involvement of sGC. Further, in whole cell mode, NO inhibited current through L-type voltage-gated Ca 2+ channels (VGCC), which was independent of both voltage and sGC. Conclusion: NO exerts sGC-independent actions at RYRs and at VGCC, both of which normally suppress cerebral artery myogenic tone.

Nostalgia, music and the television past revisited in American dreams

The 1960s-set NBC family drama American Dreams presents not just the recent American past but its musical television as well. This paper examines how the show’s recreation of and interaction with the music show American Bandstand ties together the divergent experiences of a turbulent decade. American Dreams’ reshooting and appropriation of original broadcast footage is intricately interwoven with dramatic action allowing for new layers of commentary and meaning to be read across the music and image relationship. Through intercutting and juxtaposition, its use of music performance goes beyond the regressive recycling of images of nostalgia, as critiqued by Jameson and other theorists of postmodernity, to engage political and social debates through a complex web of reference, reproduction and commentary, presenting a politicised reading of the 1960s that problematises these charges of nostalgia texts as apolitical and ‘historicist’.

Reduction of vestigial sideband effects due to multipath transmission in terrestrial broadcast television

In terrestrial television transmission multiple paths of various lengths can occur between the transmitter and the receiver. Such paths occur because of reflections from objects outside the direct transmission path. The multipath signals arriving at the receiver are all detected along with the intended signal causing time displaced replicas called 'ghosts' to appear on the television picture. With an increasing number of people living within built up areas, ghosting is becoming commonplace and therefore deghosting is becoming increasingly important. This thesis uses a deterministic time domain approach to deghosting, resulting in a simple solution to the problem of removing ghosts. A new video detector is presented which reduces the synchronous detector local oscillator phase error, caused by any practical size of ghost, to a lower level than has ever previously been achieved. From the new detector, dispersion of the video signal is minimised and a known closed-form time domain description of the individual ghost components within the detected video is subsequently obtained. Developed from mathematical descriptions of the detected video, a new specific deghoster filter structure is presented which is capable of removing both inphase (I) and also the phase quadrature (Q) induced ghost signals derived from the VSB operation. The new deghoster filter requires much less hardware than any previous deghoster which is capable of removing both I and Q ghost components. A new channel identification algorithm was also required and written which is based upon simple correlation techniques to find the delay and complex amplitude characteristics of individual ghosts. The result of the channel identification is then passed to the new I and Q deghoster filter for ghost cancellation. Generated from the research work performed for this thesis, five papers have been published. D

INDEPENDENT/NEZALEZHNI

4th Moscow Biennial/Special Project Museum Complex Mystetskyi Arsenal/Art Arsenal, Kyiv August 22 – September 13, 2011

Étant Ballet

Solo Exhibition, MacKenzie Art Gallery, Regina, Canada, The project engages with current issues around art production and food provision, catastrophe and agriculture, through the medium of a performance installation. Drawing on some of the characteristics of post dramatic theatre, the project aims to develop a new visual narratology for a contemporary art performance. A large scale video installation and construction features both as an installation site and performance set, explores the relationship between performance and food provision, looking at how changes to the organic world, the world of vibrant and edible matter might affect the way we make art. Developed and produced in collaboration with Canadian company Curtain Razors and funded by grants from Canada Council for the Arts, Saskatchewan Arts Board, the project was first commissioned by Curtain Razors and the MacKenzie Art Gallery where it was shown as a major solo exhibition as part of a series of other international programming (including artists such Guy Ben-Ner and Ron Mueck). The project was then included in the 4th Moscow Biennial as part of the landmark ‘Independent’ exhibition at the Art Arsenal in 2011. The project is planned to tour to varies other international venues throughout 2012/13. The exhibition has been reviewed by Gregory Beatty in Prairie Dog, Regina, by at the The Leader Post, The CBC French Canadian Television. Canadian writer curator Timothy Long artist and curator Elwood Jimmy have produced critical essays of the work, which will feature in a major new book, edited by Susanne Clausen, which is expected to be published in 2012. (OnCurating Publications).

Variability in fecal water genotoxicity, determined using the Comet assay, is independent of endogenous N-nitroso compound formation attributed to red meat consumption

Red meat consumption causes a dose-dependent increase in fecal apparent total N-nitroso compounds (ATNC). The genotoxic effects of these ATNCs were investigated using two different Comet assay protocols to determine the genotoxicity of fecal water samples. Fecal water samples were obtained from two studies of a total of 21 individuals fed diets containing different amounts of red meat, protein, heme, and iron. The first protocol incubated the samples with HT-29 cells for 5 min at 4 degrees C, whereas the second protocol used a longer exposure time of 30 min and a higher incubation temperature of 37 degrees C. DNA strand breaks were quantified by the tail moment (DNA in the comet tail multiplied by the comet tail length). The results of the two Comet assay protocols were significantly correlated (r = 0.35, P = 0.003), however, only the second protocol resulted in detectable levels of DNA damage. Inter-individual effects were variable and there was no effect on fecal water genotoxicity by diet (P > 0.20), mean transit time (P = 0.588), or weight (P = 0.705). However, there was a highly significant effect of age (P = 0.019). There was no significant correlation between concentrations of ATNCs in fecal homogenates and fecal water genotoxicity (r = 0.04, P = 0.74). ATNC levels were lower in fecal water samples (272 microg/kg) compared to that of fecal homogenate samples (895 microg/kg) (P < 0.0001). Failure to find dietary effects on fecal water genotoxicity may therefore be attributed to individual variability and low levels of ATNCs in fecal water samples.