12,300 research outputs found
In vivo Ca2+ dynamics induced by Ca2+ injection in individual rat skeletal muscle fibers
Get PDFCitation: Wakizaka, M., Eshima, H., Tanaka, Y., Shirakawa, H., Poole, D. C., & Kano, Y. (2017). In vivo Ca2+ dynamics induced by Ca2+ injection in individual rat skeletal muscle fibers. Physiological Reports, 5(5), 10. doi:10.14814/phy2.13180In contrast to cardiomyocytes, store overload-induced calcium ion (Ca2+) release (SOICR) is not considered to constitute a primary Ca2+ releasing system from the sarcoplasmic reticulum (SR) in skeletal muscle myocytes. In the latter, voltage-induced Ca2+ release (VICR) is regarded as the dominant mechanism facilitating contractions. Any role of the SOICR in the regulation of cytoplasmic Ca2+ concentration ([Ca2+](i)) and its dynamics in skeletal muscle in vivo remains poorly understood. By means of in vivo single fiber Ca2+ microinjections combined with bioimaging techniques, we tested the hypothesis that the [Ca2+](i) dynamics following Ca2+ injection would be amplified and fiber contraction facilitated by SOICR. The circulation-intact spinotrapezius muscle of adult male Wistar rats (n = 34) was exteriorized and loaded with Fura-2 AM to monitor [Ca2+](i) dynamics. Groups of rats underwent the following treatments: (1) 0.02, 0.2, and 2.0 mmol/L Ca2+ injections, (2) 2.0 mmol/L Ca2+ with inhibition of ryanodine receptors (RyR) by dantrolene sodium (DAN), and (3) 2.0 mmol/L Ca2+ with inhibition of SR Ca2+ ATPase (SERCA) by cyclopiazonic acid (CPA). A quantity of 0.02 mmol/L Ca2+ injection yielded no detectable response, whereas peak evoked [Ca2+](i) increased 9.9 +/- 1.8% above baseline for 0.2 mmol/L and 23.8 c 4.3% (P < 0.05) for 2.0 mmol/L Ca2+ injections. The peak [Ca2+](i) in response to 2.0 mmol/L Ca2+ injection was largely abolished by DAN and CPA (-85.8%, -71.0%, respectively, both P < 0.05 vs. unblocked) supporting dependence of the [Ca2+](i) dynamics on Ca2+ released by SOICR rather than injected Ca2+ itself. Thus, this investigation demonstrates the presence of a robust SR-evoked SOICR operant in skeletal muscle in vivo
Exercise-induced pulmonary hemorrhage: where are we now?
Get PDFCitation: Poole, D. C., & Erickson, H. H. (2016). Exercise-induced pulmonary hemorrhage: where are we now? Veterinary Medicine-Research and Reports, 7, 133-148.
https://doi.org/10.2147/vmrr.s120421As the Thoroughbreds race for the final stretch, 44 hooves flash and thunder creating a cacophony of tortured air and turf. Orchestrated by selective breeding for physiology and biomechanics, expressed as speed, the millennia-old symphony of man and beast reaches its climax. At nearly 73 kilometers per hour (45 mph) over half a ton of flesh and bone dwarfs its limpet-like jockey as, eyes wild and nostrils flaring, their necks stretch for glory. Beneath each resplendent livery-adorned, latherin-splattered coat hides a monstrous heart trilling at 4 beats per second, and each minute, driving over 400 L (105 gallons) of oxygen-rich blood from lungs to muscles. Matching breath to stride frequency, those lungs will inhale 16 L (4 gallons) of air each stride moving >1,000 L/min in and out of each nostril - and yet failing. Engorged with blood and stretched to breaking point, those lungs can no longer redden the arterial blood but leave it dusky and cyanotic. Their exquisitely thin blood-gas barrier, a mere 10.5 mu m thick (1/50,000 of an inch), ruptures, and red cells invade the lungs. After the race is won and lost, long after the frenetic crowd has quieted and gone, that blood will clog and inflame the airways. For a few horses, those who bleed extensively, it will overflow their lungs and spray from their nostrils incarnadining the walls of their stall: a horrifically poignant canvas that strikes at horse racing's very core. That exercise-induced pulmonary hemorrhage (EIPH) occurs is a medical and physiological reality. That every reasonable exigency is not taken to reduce/prevent it would be a travesty. This review is not intended to provide an exhaustive coverage of EIPH for which the reader is referred to recent reviews, rather, after a brief reminder of its physiologic and pathologic bases, focus is brought on the latest developments in EIPH discovery as this informs state-of-the-art knowledge, the implementation of that knowledge and recommendations for future research and treatment
Women and words poetry and a story written and read by Fiona Farrell Poole.
No full textPoole reads a story titled "Night grown" and a selection of poems, most of which come from her collection titled "Hard rocks".From a recording made by David Drummond at the "Women and words" reading session at the Manawatu Art Gallery, Palmerston North, 9 November 1987.Dubbed by the Stout Research Centre Literary Archive
The Poole Iron Age Logboat
Get PDFThis book is the culmination of significant multi-disciplinary work carried out by a variety of specialists, from conservators to woodworking and boatbuilding experts, exploring the history of the Poole Iron Age logboat (today imposingly ..
Developing a partnership of indigenous peoples, conservationists, and land use planners in Latin America
Get PDFIllustrating from a rich body of case material, Poole's report reflects a shift away from the traditional view - represented by certain national parks and similar protected areas - that indigenous peoples be allowed to occupy and use an area's resources following rules set by conservationists. Under the new paradigm that is developing, indigenous peoples are seen as an integral part of protected area planning through agreements worked out in partnership with conservation authorities. An example of this new approach is the role that indigenous peoples are playing in the design of biosphere reserves. Poole suggests that the Bank and other development organizations pay more attention to vernacular economies - economies based on local resources, used either for subsistence or as a source of revenue. He also recommends more research into economics and resource implications of these local activities to harvest wild resources, especially in environmentally delicate areas such as tropical rainforests.Environmental Management,Tourism and Ecotourism,Water Conservation,Natural Resources Management,Wetlands
Rules-of-thumb for guiding monetary policy
Get PDFThis article was originally published in the Board of Governors of the Federal Reserve System Open Market Policies and Operating Procedures-Staff Studies, July 1971. It is reprinted here as an addendum to these conference proceedings.Transparency ; Monetary policy
Panel C: Author-Meets-Readers Session
No full textAuthor David Webber discusses his book The Rise of the Working Class Shareholder: Labor\u27s Last Best Weapon published on Harvard University Press
Cult: A Composite Novel
Get PDFCult (redacted)
The first component of the thesis is a composite novel called Cult which falls into two parts with seven narratives in each. Part 1 tracks the protagonist, Ellen, from her first involvement with the cult through to her eventually leaving it. Although fiction, the first half of the book answers the kinds of questions the author is asked when people discover that she was once a sannyasin (a follower of the guru Bhagwan Shree Rajneesh). While the experiences of meditation, group therapy and communal living are all faithfully rendered within the stories, the need for strong characters, narrative drive and a lightness of touch takes precedence.
Part 2 picks up Ellen’s story some twenty or so years later and explores what becomes of her in middle age. It also looks at other groups in society, such as academia, the law and the internet dating community which each have their own jargon, hierarchies, rituals and rules but are not considered to be cults.
The book examines the question raised in the Epigraph, ‘how do we be together when we feel so alone’ with a focus on relationships other than the familial and the romantic.
Collisions, Chasms and Connections: a Performative Exploration of the Composite Novel Form
The second part of the thesis is both a critical and creative response to three contemporary American books: Olive Kitteridge by Elizabeth Strout; A Visit from the Goon Squad by Jennifer Egan; and Legend of a Suicide by David Vann. The critical element comprises a close reading of the three books; a chronological reconstruction of their overarching storylines; and a consideration of what their authors have said about writing the books. It concludes that, in the composite novel, the simultaneous presentation of multiple views and storylines operate much like a 3D image to give the impression of depth to the characters and situations rendered. The creative element of the essay is a playful and personal response to the texts
Effect of pulmonary emphysema on diaphragm capillary geometry
No full text Poole, David C., and Odile Mathieu-Costello. Effect of pulmonary emphysema on diaphragm capillary geometry. J. Appl. Physiol. 82(2): 599–606, 1997.—In emphysema, the diaphragm shortens by losing sarcomeres. We hypothesized that unless capillaries undergo a similar shortening, capillary geometry must be altered. Without quantifying this geometry, capillary length and surface area per fiber volume, which are critical measurements of the structural potential for blood-tissue exchange, cannot be resolved. Five months after intratracheal elastase (E) or saline (control; C) instillation, diaphragms from male Syrian golden hamsters were glutaraldehyde perfusion fixed in situ at reference lung positions (residual volume, functional residual capacity, total lung capacity) to provide diaphragms fixed over a range of sarcomere lengths. Subsequently, diaphragms were processed for electron microscopy and analyzed morphometrically. Emphysema increased lung volume changes from −20 to 25 cmH2O airway pressure (i.e., passive vital capacity) and excised lung volume (both P < 0.001). In each region of the costal diaphragm (i.e., ventral, medial, dorsal), sarcomere number was reduced (all P < 0.05). Capillary-to-fiber ratio increased (C = 2.2 ± 0.1, E = 2.8 ± 0.1; P < 0.01) and fibers hypertrophied (C = 815 ± 35, E = 987 ± 67 μm2; P < 0.05; both values at 2.5 μm sarcomere length). Capillary geometry was markedly altered by the loss of sarcomeres in series. Specifically, the additional capillary length derived from capillary tortuosity and branching was increased by 183% at 2.5 μm sarcomere length compared with C values (C, 359 ± 43; E, 1,020 ± 158 mm−2, P < 0.01). This significantly increased total capillary length (C, 3,115 ± 173; E, 3,851 ± 219 mm−2 at 2.5 μm, P < 0.05) and surface area (C, 456 ± 13; E, 519 ± 24 cm−1, P < 0.05) per fiber volume. Thus emphysema substantially alters diaphragm capillary geometry and augments the capillary length and surface area available for blood-tissue exchange. </jats:p
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