Myocardial perfusion imaging and coronary angiography in patients with known or suspected stable angina pectoris.

INTRODUCTION: The patho-physiological cause of angina pectoris is myocardial ischaemia, which can be objectified by myocardial perfusion imaging (MPI). METHODOLOGY: MPI was undertaken prior to coronary angiography (CAG) in 86 randomly selected patients with known or suspected stable angina pectoris. RESULTS: Among 78 adequately stressed patients, MPI was normal in 28 (36%) and showed reversible and irreversible perfusion abnormalities in 30 (38%) and 20 patients (26%), respectively. Coronary angiograms were normal in 28 (36%) and revealed at least one > or = 50% stenosis in 50 patients (64%) (16 with single and 34 with multi vessel disease). Using angiography as a reference, the sensitivity and specificity of MPI in detecting coronary artery disease was 88% and 93%, respectively. DISCUSSION: MPI demonstrates regional hypoperfusion whereas CAG depicts anatomical stenosis in epicardial arteries. Both modalities are potentially relevant in patients with stable angina pectoris. The functional significance of coronary artery lesions is, however, variable and MPI can demonstrate normal myocardial perfusion in the presence of moderate lesions. MPI exhibited a high sensitivity and specificity regarding significant lesions. More than one third of the subjects had a normal MPI and a normal CAG. Patients with stable angina pectoris and a normal MPI have a very low risk of cardiac events and do usually not require further invasive investigation or therapy. Reversible ischaemia and irreversible ischaemia with demonstration of viable tissue call for coronary revascularisation.

[Myocardial scintigraphy and coronary arteriography in patients with known or suspected stable angina pectoris]. / Myokardiescintigrafi og koronararteriografi hos patienter med kendt eller formodet stabil angina pectoris.

INTRODUCTION: Myocardial perfusion imaging (MPI) demonstrates regional hypoperfusion, whereas coronary angiography shows anatomical stenoses in epicardial arteries. Both modalities are potentially relevant in patients with stable angina pectoris. MATERIALS AND METHODS: MPI was undertaken before angiography in 86 randomly selected patients with stable angina pectoris. RESULTS: Of 78 adequately stressed patients, MPI was normal in 28 (36%) and showed reversible and irreversible perfusion abnormalities in 30 (38%) and 20 patients (26%), respectively. Coronary angiograms were normal in 28 (36%) and revealed at least one > or = 50% stenosis in 50 patients (64%) (16 with single vessel and 34 with multivessel disease). With angiography as reference, the sensitivity and specificity of MPI in the detection of coronary artery disease were 88% and 93%, respectively. DISCUSSION: Patients with stable angina pectoris and a normal MPI have a very low risk of cardiac events and do not usually require invasive investigation and therapy. Reversible ischaemia and irreversible ischaemia with viable tissue call for coronary revascularisation.

The genetic switch regulating activity of early promoters of the temperate lactococcal bacteriophage TP901-1.

A functional analysis of open reading frame 4 (ORF4) and ORF5 from the temperate lactococcal phage TP901-1 was performed by mutant and deletion analysis combined with transcriptional studies of the early phage promoters p(R) and p(L). ORF4 (180 amino acids) was identified as a phage repressor necessary for repression of both promoters. Furthermore, the presence of ORF4 confers immunity of the host strain to TP901-1. ORF5 (72 amino acids) was found to be able to inhibit repression of the lytic promoter p(L) by ORF4. Upon transformation with a plasmid containing both ORF4 and ORF5 and their cognate promoters, clonal variation is observed: in each transformant, either p(L) is open and p(R) is closed or vice versa. The repression is still dependent on ORF4, and the presence of ORF5 is needed for the clonal variation. Induction of a repressed p(L) fusion containing orf4 and orf5 was obtained by addition of mitomycin C, and the induction was also shown to be dependent on the presence of the RecA protein, even though ORF4 does not contain a recognizable autocleavage site. Our results suggest that the relative amounts of the two proteins ORF4 and ORF5 determine the decision between lytic or lysogenic life cycle after phage infection and that a protein complex consisting of ORF4 and ORF5 may constitute a new type of genetic switch in bacteriophages.

Coronary heart disease in Norwegian sea-pilots: part of the occupational hazard?

A near maximal bicycle exercise test revealed a prevalence of positive exercise ECG's of 8/68 among apparently healthy sea-pilots and 93/2014 among apparently healthy men of comparable age in Oslo (P less than 0.01). This difference could not be explained in terms of differences in commonly accepted coronary heart disease risk factors (cholesterol/triglycerides, smoking habits and blood pressure). Reasons for the difference should be sought in the working environment of the pilots as well as in possible unfavourable life habits adapted during leisure time as indicated by a relative increase in body weight and somewhat lower working capacity in pilots than in age matched counterparts from Oslo.