The Friedewald equation tends to underestimate LDL-C most when accuracy is most crucial. Especially if triglyceride levels are ≥ 150 mg/dl, Friedewald estimation commonly classifies LDL-C as <70 mg/dl despite directly measured levels ≥ 70 mg/dl, and therefore additional evaluation is warranted in high-risk patients.

Monoamine oxidase (MAO) exists in two forms distinguishable by substrate specificity. Inhibition of MAO A is believed to be responsible for the antidepressant activity of MAO inhibitors. A group of N-arylacetamides are highly specific inhibitors of MAO A, some with IC50 values in the 10-100 nM range. The requirements for high activity and specificity include a nearly linear tricyclic aromatic portion but a larger and a smaller central ring component. The amide group, which is best acetamido, is optimally placed para to the smaller central group. The size and shape of the aromatic moiety appear to be the major influence on activity and specificity for MAO A.

ObjectiveProgression of carotid intima-media thickness (CIMT) is a surrogate indicator for the early stages of atherosclerosis.MethodsThe study investigated relationships between baseline lipoprotein cholesterol, triglyceride (TG), and apolipoprotein (Apo) B levels assessed with density gradient ultracentrifugation (DGU) and progression of posterior wall common CIMT in men (45–75 years of age) and women (55–74 years of age) in the control arm of a clinical trial. Participants had baseline posterior wall CIMT 0.7–2.0 mm, without significant stenosis. CIMT was assessed using B-mode ultrasound at baseline, and 12 and ~18 months. A DGU cholesterol panel that assessed the major lipoprotein classes and subclasses, plus triglycerides, lipoprotein (a) cholesterol, low-density lipoprotein (LDL) peak time (inversely related to LDL particle density), and Apo B were performed on fasting baseline samples. Apo B was also measured using an enzyme linked immunosorbent assay.ResultsBaseline CIMT was inversely associated (P < 0.001) with CIMT progression. After adjustment for baseline CIMT, significant predictors of posterior wall CIMT progression in linear regression analyses included LDL peak time (inverse, P = 0.045), total high-density lipoprotein cholesterol (HDL-C) (inverse, P = 0.001), HDL2-C (inverse, P = 0.005), HDL3-C (inverse, P = 0.003), very low-density lipoprotein (VLDL)-C (P = 0.037), and VLDL1+2-C (P = 0.016).ConclusionThese data indicate that DGU-derived indicators of the “atherogenic lipoprotein phenotype,” including increased TG-rich lipoprotein cholesterol, lower HDL-C and HDL-C subfractions, and a greater proportion of LDL-C carried by more dense LDL particles, are associated with CIMT progression in men and women at moderate risk for coronary heart disease.

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