Early exercise thallium-201 single photon emission computed tomography in unstable angina: a prospective study.

To evaluate the safety and diagnostic value of early symptom-limited exercise electrocardiography (ECG) and exercise thallium-201 single photon emission computed tomography (SPECT) in unstable angina (UA), 39 patients were studied prospectively soon after stabilization on medical treatment. No patient had a history of myocardial infarction (MI) or revascularization and patients with left bundle branch block were excluded. Exercise ECG and exercise thallium-201 SPECT were performed 8 +/- 4 days and 11 +/- 6 days respectively after admission to hospital. Seventeen out of 39 patients (44%) had positive exercise ECGs and 22 (56%) negative or inconclusive ones. Exercise thallium-201 SPECT was positive in 26 patients (67%) and negative in 13 patients (33%). Thirty-one patients underwent coronary arteriography and 24 of them proved to have significant coronary artery disease (CAD). The sensitivity, specificity and positive predictive value of exercise ECG in detecting CAD are 62%, 86%, and 94% respectively while the corresponding results are 96%, 100%, and 100% for exercise thallium-201 SPECT. Therefore, it is concluded that the early symptom-limited exercise test is safe in medically stabilized patients with UA. Early exercise thallium-201 SPECT is highly sensitive and predictive of the presence of significant CAD among patients in the early recovery phase of UA and can be used in selecting this group of patients for coronary angiography and other therapeutic strategies.

The formation of gamma-caseins during cooling of raw milk.

It has been shown that there is a time-dependent transfer of beta-casein and the milk serine proteinase system from micelles to milk serum with change of temperature from 38 to 4 degrees C. It has been established that the gamma-caseins can be formed by proteolytic degradation of beta-casein. By a simple extraction technique, the very hydrophobic gamma-casein fraction was separated from stored milks (26 and 4 degrees C) and estimated quantitatively. The results showed that the proteolytic degradation of beta-casein is faster at 4 degrees C than at room temperature and this can be explained by the immobilization of enzyme and substrate at the micelle surface at higher temperatures (26 degrees C). The results indicate that irreversible changes during cooling for short periods do not cause problems in milk processing, but the formation of gamma-caseins and phosphopeptides may influence the technological properties of raw milk stored for more than 48 h.