No abstract

Background -Transfer factor of the lung for carbon monoxide (TLCO) was measured by a new method based on analysis ofthe ratio ofthe concentrations ofcarbon monoxide to an inert gas (methane) TLCO (TLCo,bh) is based on the Bohr equation which states that for any TLCO, at constant lung volume, gas absorption is proportional to time of breath holding (see below). The breath holding method is particularly prone to problems because, during both inspiratory and expiratory flow, gas absorption follows patterns which are different from breath holding"4; an "equivalent" breath holding time during these phases of respiration is estimated to account for the differing gas absorption patterns.2With the introduction of rapid gas analysers an alternative approach to TLco,bh has become available. Gas diffusion during constant exhalation has been analysed theoretically.34 Such an approach does not depend upon length of time or other conditions during either inspiration or breath holding. Although mathematical analysis of gas absorption during constant exhalation suggests that the absorption of carbon monoxide is proportional to the relative rate of change of lung volume,34 several studies have calculated TLCo by using breath holding equations over discrete decrements of lung volume -for example, 2% or 10% vital capacity -with or without smoothing of data.5'9We describe here a method which uses constant exhalation following minimal breath holding developed from a theoretical analysis of gas diffusion and absorption during constant exhalation.34 Comparison TLCO data for 100 patients between this new exhalation technique (TLco,ex) and TLco,bh are also presented. Methods THEORYThe breath holding method is based on an idealised breathing manoeuvre during which inspiratory and expiratory phases are accounted for as "equivalent" breath holding time.

No abstract

This essay reads Robert Coover's novel Pricksongs and Descants as an instance of the interchange between mimetic representation and literary self-reflexivity characteristic of postmodern novelists such as Vladimir Nabokov or John Barth. It analyses some of the short stories collected in this volume as examples of Coover's ongoing concern with the interchange between (1) our perception of the real, (2) the systems of thought by means of which we account for the flux of reality, and (3) the epistemological nature and function of literature as a vehicle for modern self-understanding. The result is not only a (literary) experiment in which the structures of the traditional, linear novel are relentlessly questioned, but also an inquiry into the possibility of tracing a clear-cut distinction between fiction and reality and, subsequently, between art and life.Besides dealing with mimetic forms of various kinds in earlier fictions, notably in The Origin of the Brunists (1966) and The Universal Baseball Association (1968), Robert Coover has also explored the implications of mimetic representation in the specific context of literary texts. The short stories collected in Pricksongs and Descants (1969), most of them written and published in American journals and magazines before the appearance of his first novel, explicitly examine fundamental aesthetic categories by throwing them into question. Pricksongs and Descants is in fact a collection of experimental short stories whose concern is the very limits of literary representation. The role of the author, the narrative line, the boundary between reality and fantasy, and other concepts and paradigms are examined in a set of short fictions that deals with the question of meaning-and fictionmaking in the universe of literary production. In his third published book, then, Coover plunges into the field of storytelling and thereby narrows the exploratory breadth of his earlier works. And although in fact some of the issues he delves into could be metaphorically expanded in order to embrace other non-fictional representational processes, here I prefer to limit my analysis to the strictly literary concerns of the anthology.

Oxidative stress is associated with development and progression of cardiovascular disease. Angiotensin II produces oxidative stress and endothelial dysfunction, and its actions may be attenuated by the activity of angiotensin converting enzyme type 2 (ACE2) which converts angiotensin II to the vasoprotective peptide angiotensin (1-7). Similarly, increased oxidative stress is associated with aortic valve stenosis in humans and mice. In my thesis studies, I explore mechanisms of modulation and generation of oxidative stress in cerebral arteries and heart valves. First, I tested the hypothesis that ACE2 deficiency increases oxidative stress and vasomotor dysfunction in cerebral arteries, and examined the role of ACE2 in vascular aging. Vasomotor function was assessed in the basilar artery ex vivo of adult and old