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Objective: To describe the extent and distribution of coronary artery luminal narrowing in a Canadian population (aged 40 years and under) dying suddenly and unexpectedly., Methods: From a coroner's autopsy population of 350 subjects whose mean age was 28.4 +/- 6.5 years and of whom 250 were male, percentage luminal narrowing was estimated in the four epicardial coronaries. The left main, left anterior descending, left circumflex and right major coronary arteries were sectioned at 5 mm intervals and percentage cross-sectional luminal narrowing from the internal elastic lamina of each segment was estimated microscopically and then graded into four categories: I, 0 to 25%; II, 26 to 50%; III, 51 to 75%; and IV, greater than 75%. A total of 14,611 5 mm segments were evaluated (mean 41.7 per case). The segments were classified as originating from males or females and into three age groups (less than 20, 20 to 29 and 30 to 40 years)., Results: For the entire population, virtually no luminal narrowing greater than 50% was found in patients less than age 20 years, but was found in 3% of segments in the group aged 20 to 29 years and in 8.4% of segments in the group aged 30 to 40 years. In the group aged 20 to 29 years, greater than 50% narrowing was found in 3.8% of segments in males and in 1.2% of segments in females (P < 0.001). In the group aged 30 to 40 years, the corresponding numbers were 10.5% for males and 2.2% in females (P < 0.0001). Eighty-six males (34.4%) had greater than 50% narrowing of at least one coronary artery versus 19 females (19%) (P < 0.01). Left main narrowing of greater than 50% was found in 17 subjects, of which 13 were males. Luminal narrowing was more prevalent in the left anterior descending than the right coronary artery or left circumflex coronary artery and more prevalent in the right coronary artery than the left circumflex coronary artery., Conclusions: In subjects less than age 20 years, luminal narrowing greater than 50% was virtually nonexistent. Its frequency progressed in both sexes after age 20 years and was significantly more pronounced in males. Narrowing of the left main coronary artery was more frequent than anticipated and was more common in males.

Mitotic HeLa cells collected by shake-off synchronization with minimum perturbation showed a reduced rate of protein synthesis which began to fall 15-30 min after metaphase, and at its lowest fell to 55-65% of the average interphase value in late metaphase. Similar rate determination with 3H-leucine incorporation in synchronous M-phase cells moving out of mitosis indicated that the protein synthetic rate had returned to nearly normal interphase levels by the end of telophase. RNA synthesis measured with 3H-uridine pulses showed a similar pattern of suppression, with a low of 25-35% the interphase rate in metaphase/anaphase and a return to control levels within about 15-30 min of the start G1. The downturns in both protein and RNA synthesis were progressive and greatly pronounced in cells prevented from leaving metaphase by alkaloid treatment. Further studies are reported on the separate and combined effects of action of actinomycin D and alkaloids on macromolecular synthesis in cells entering and leaving M-phase. The findings suggest that only a transient and partial suppression of protein and RNA synthesis occurs during mitosis, a situation which can lead to exaggerated and progressive decline of these activities in cells which are not permitted to complete mitosis on schedule.

A new method is described for measurement of gallbladder volume based on three-dimensional single photon emission computed tomography (SPECT). The technique was first validated in a body phantom that used a balloon to represent the gallbladder. The balloon was inflated with a known volume and SPECT volume was calculated by summing the voxels in each transaxial slice above a percentage count threshold. The SPECT and true volume showed a high linear correlation between 15 to 90 ml (r = 0.99). The mean fasting gallbladder volume using a technetium-99m-labelled hepatobiliary agent in nine normal subjects was 26 +/- 2 ml (range 18 to 39 ml). By combining the SPECT measurement with a planar technique, it was also possible to evaluate gallbladder emptying parameters. Following a 3 min infusion of 10 ng kg-1 of cholecystokinin octapeptide (CCK), the mean gallbladder ejection rate was 1.2 +/- 0.2 ml min-1 and the residual volume was 12 +/- 2 ml. SPECT offers a new noninvasive method for accurate measurement of gallbladder volume.