instruction:
Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.
question:
Abstract: Atrial pacing was performed in 16 patients with angina at rest and significant coronary artery stenosis (greater than 70%) over 2 consecutive days in the morning (10 A.M. to 1 P.M.), in the afternoon (4 to 7 P.M.), and at night (12 midnight to 3 A.M.) to assess possible circadian variations of their ischemic threshold. Overall, the incidence of resting angina was highest at night. All pacing results were positive (greater than or equal to 1.0 mm ST segment shift) and tended to be reproducible in nine patients, whereas some or all were negative in seven. Among all positive results, ischemic thresholds at night were significantly lower than those in the morning and in the afternoon (125 +/- 3 vs 138 +/- 3 and 139 +/- 2 beats/min, mean +/- SEM; p less than .005). In nine patients, 19 pacing tests produced ST segment elevation, of which 13 were performed at night (68%). We conclude that patients with resting angina and severe coronary stenosis often exhibit a nocturnal decline in their ischemic threshold, which seems to facilitate development of transmural ischemia during atrial pacing.
answer:
Resting angina with fixed coronary artery stenosis: nocturnal decline in ischemic threshold.

question:
Abstract: A patient is presented who developed chloracne after exposure to lumber which was pressure-treated with pentachlorophenol (PCP). It was presumed that his disease arose via percutaneous absorption of polychlorinated aromatic compounds (dioxins and furans) which are known to contaminate technical grade PCP. The patient's condition improved after treatment with oral isotretinoin.
answer:
Chloracne from pentachlorophenol-preserved wood.

question:
Abstract: This study demonstrates that 20 to 30 microns porous, Replamineform silicone rubber prostheses remain isocompliant with adjacent arterial segments up to 8 months following implantation. This finding contrasts with the results of currently available prostheses, including autologous vein, which rapidly become minimally compliant. We conclude that this vascular construction is stable over the long-term following implantation and may improve the success of small internal diameter arterial reconstruction by eliminating failures caused by intimal hyperplasia.
answer:
Maintenance of compliance in a small diameter arterial prosthesis.