Aleatory Processes in Nature as Artistic Theme

&nbsp; The intent of my creative work has been to explore forms and formal situations that derive from natural occurrences which appear on a level of normal vision to be transient and/or aleatory. This work is intended to expand my own receptivity (and hopefully that of the spectator) to that which may be perceived as visually interesting in general experience. This exploration has not precluded the possibility of non-random, overtly purposive visual elements as relevant factors in my work. Indeed, the juxtaposition of orderly, symmetrical elements with random themes, imagery, or intentions is perhaps a most encompassing and inevitable perception of the physical world and Man's part in it. It has been my intention to extend my awareness of the visual and physical environment as completely as possible.</p

Sustained antianginal efficacy of transdermal nitroglycerin patches using an overnight 10-hour nitrate-free interval

The antianginal efficacy of the transdermal nitroglycerin patch may be limited by the rapid development of tolerance during uninterrupted exposure. To address this problem, we investigated the role of intermittent therapy was investigated, using a daily nitroglycerin patch-free Interval in 13 patients with chronic stable angina. Concomitant antianginal medications were permitted. Entry criteria required reproducible exercise times to both onset of angina and 1 mm of ST-segment depression. In each patient the highest tolerated nitroglycerin patch dose was determined by a dose-titration phase, which was then used in a double-blind crossover trial comprising 2 randomized treatment arms: 1 week of active nitroglycerin patch and 1 week of matching placebo. All patches were worn only from 8 a.m. to 10 p.m. daily. Exercise testing was repeated before patch application and then 4 and 8 hours after application on both the first and the last day of each treatment arm. Eleven patients completed the randomized crossover phase. Exercise time to the onset of angina and to the onset of 1 mm of ST-segment depression was significantly prolonged during the first day of therapy at both 4 and 8 hours after active nitroglycerin patch application compared with placebo (p \u3c 0.01). During sustained use, the benefit at 4 and 8 hours after nitroglycerin patch application was still evident (p \u3c 0.001 and p \u3c 0.05, respectively). No evidence of a overnight rebound or withdrawal phenomenon was observed by history or by ambulatory Hotter monitoring calibrated for ST-segment analysis. The results suggest that tolerance to the antianginal effects of the nitroglycerin patch can be avoided by providing a dosing regimen using interrupted exposure to nitroglycerin. © 1988

Prevention of nitrate tolerance with angiotension converting enzyme inhibitors

Background. Activation of neurohumoral hormones or sulfhydryl group depletion may contribute to the development of nitroglycerin tolerance. In an attempt to prevent nitrate tolerance, this study evaluated the interaction of nitroglycerin with angiotensin converting enzyme (ACE) inhibitors with and without a sulfhydryl group. Methods and Results. Thirty-four subjects were randomized to a 7-day regimen of enalapril 10 mg b.i.d., captopril 25 mg t.i.d., or placebo. Venodilator response to nitroglycerin was assessed with forearm plethysmography by measuring the change in venous volume after administration of 0.4 mg sublingual nitroglycerin. Plethysmographic measurements were obtained serially 1) at baseline, 2) after 4 days of ACE inhibitor or placebo, 3) 2 hours after application of a 10 mg/24 hr nitroglycerin patch, and 4) 74 hours after continuous nitropatch application. ACE inhibition alone caused no significant change in the response to sublingual nitroglycerin. Nitrate response remained unchanged after 2 hours ( acute ) of nitropatch exposure in all three groups. After 74 hours ( chronic ) of continuous nitropatch application, the venodilator response to sublingual nitroglycerin was reduced by 40% in the placebo group, 10% in the enalapril group, and 2% in the captopril group. This attenuation was significant only in the placebo group (p\u3c0.01). Pairwise comparison of nitrate response between groups was significantly different between the captopril and placebo groups (p\u3c0.01) and between the placebo and enalapril groups (p\u3c0.05). Plasma renin levels increased equally in the enalapril and captopril groups. Body weight increased only in the placebo group, suggesting prevention of nitrate-induced volume expansion in the ACE inhibitor groups. Conclusions. This study demonstrates that ACE inhibitors may prevent nitrate tolerance to long-term nitrate therapy

Efficacy of oral diltiazem to control ventricular response in chronic atrial fibrillation at rest and during exercise

Although digpxin is often the first choice for control of ventricular response in chronic atrial fibrillation, it fails to slow exercise rates. Diltiazem, a calcium channel antagonist that slows atrioventricular conduction, was administered to 16 patients who failed to achieve adequate rate control on low level exercise testing despite digoxin therapy. Therapeutic response to diltiazem was assessed with submaximal and maximal exercise tests and 24 hour ambulatory electrocardiographic monitoring. During the diltiazem treatment phase, ventricular response at rest diminished (96 ± 17 versus 69 ± 10 beats/min, p \u3c 0.001) as did rate during submaximal exercise (155 ± 28 versus 116 ± 26, p \u3c 0.001), maximal exercise (163 ± 14 versus 133 ± 26, p \u3c 0.001) and average ventricular response during 24 hour monitoring (87 ± 13 versus 69 ± 10, p \u3c 0.001). Rate at rest decreased 26 ± 15% and submaximal exercise rate diminished 24 ± 12%. Thirteen (81%) of the 16 patients exhibited at least 15% slowing of rate at rest and during submaximal exercise. Eleven patients (69%) reported alleviation of symptoms. There was no change in serum digoxin levels during diltiazem treatment (1.3 ± 0.5 versus 1.3 ± 0.6 ng/ml, p = NS). On withdrawal of diltiazem, ventricular response returned to baseline values. Diltiazem is an effective agent for control of ventricular response, both at rest and during exercise, in digoxin-treated patients with chronic atrial fibrillation. © 1987, American College of Cardiology Foundation. All rights reserved

Kingston Group Exhibition, 1986

Workman notes the importance of Kingston Artists' Association to the 11 artists exhibited. Includes biographical notes and artists' statements. 1 bibl. ref

Réflexion sur un sentiment rural

Documentation of a touring exhibition dedicated to Jack Chambers (1931-1978) and gathering works by 17 Ontario artists committed to the decentralization philosophy adopted by Peterborough's Artspace centre. Includes a historical survey of the first five years of the centre. Statements by the artists and Chambers. Biographical notes. 3 bibl. ref

Oh Canada!

Resembling a Canadian passport, this catalogue represents works by over 20 artists addressing Canadian identity and history. Statements by the artists. Biographical notes

Reactions of Ionised Pryridazine, 2-Aminopyrazine and 2-Aminopyridine and their a-Distonic Isomers.

NoThe reactions of ionised pyridazine, aminopyrazine and aminopyridine and the corresponding ¿-distonic ions are examined by a combination of tandem mass spectrometric techniques, including analysis of metastable ion (MI), collision induced dissociation and neutralisation¿reionisation mass spectra (NRMS). Further insight into the relative stability and energy barriers towards tautomerism of each ionised heterocycle with its ¿-distonic isomer is obtained by computational methods. In all these systems, both the conventional radical-cation and the ¿-distonic tautomer are stable species which exist in discrete energy wells, with a significant barrier towards their interconversion. Although each ¿-distonic ion is sufficiently stable to survive neutralisation¿reionisation, the conventional ionised heterocycle is more stable in each case. The possibility of investigating proton-transport catalysis in the tautomerism of these ionic systems is discussed