C-declination curve (a result of the atomic bomb tests in the
1950s and 1960s) to determine the average biological age of carotid
plaques.C
content by accelerator mass spectrometry. The average plaque age (i.e.
formation time) was 9.6±3.3 years. All but two plaques had formed
within 5–15 years before surgery. Plaque age was not associated with
the chronological ages of the patients but was inversely related to plasma
insulin levels (p = 0.0014). Most plaques were
echo-lucent rather than echo-rich (2.24±0.97, range 1–5).
However, plaques in the lowest tercile of plaque age (most recently formed)
were characterized by further instability with a higher content of lipids
and macrophages (67.8±12.4 vs. 50.4±6.2,
p = 0.00005; 57.6±26.1 vs. 39.8±25.7,
p<0.0005, respectively), less collagen (45.3±6.1 vs.
51.1±9.8, p<0.05), and fewer smooth muscle cells (130±31
vs. 141±21, p<0.05) than plaques in the highest tercile.
Microarray analysis of plaques in the lowest tercile also showed increased
activity of genes involved in immune responses and oxidative
phosphorylation.C, can improve our understanding of carotid
plaque stability and therefore risk for clinical complications. Our results
also suggest that levels of plasma insulin might be involved in determining
carotid plaque age