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1.  Peripheral artery disease, biomarkers, and darapladib 
American heart journal  2011;161(5):972-978.
Objective
Subjects with peripheral artery disease (PAD) are at increased risk of cardiovascular morbidity and mortality, perhaps in part, related to increased levels of inflammation, platelet activity, and lipids. We therefore sought to investigate the relationship between PAD and levels of inflammatory, platelet, and lipid biomarkers and the treatment effect of darapladib, a novel lipoprotein-associated phospholipase A2 (Lp-PLA2) inhibitor.
Methods
This is a post hoc analysis of the 959 patients with coronary disease or their risk equivalent receiving atorvastatin who were randomized to receive darapladib or placebo to examine the effects of an Lp-PLA2 inhibitor on the biomarkers of cardiovascular risk. We conducted an exploratory analysis evaluating the levels of biomarkers in subjects with PAD (n = 172) compared with those without PAD (n = 787).
Results
After adjustment for age, sex, smoking, body mass index, and diabetes, subjects with PAD had greater levels of matrix metalloproteinase-9 (between group comparisons 22%, 95% confidence interval [10–31], P < .01), myeloperoxidase (12% [2–20], P = .01), interleukin-6 (13% [4–21], P = .01), adiponectin (17% [7–26], P < .01), intercellular adhesion molecule-1 (7% [2–11], P < .01), osteoprotegrin (6% [1–10], P = .02), CD40 ligand (15% [1–28], P = .04), high-sensitivity C-reactive protein (17% [1–31], P = .04), and triglycerides (11% [0.2–21], P = .05). No significant difference was detected for Lp-PLA2 activity, P-selectin, urinary 11-dehydrothroboxane B2, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol between subjects with and without PAD. Darapladib produced highly significant inhibition of Lp-PLA2 activity when compared with placebo at weeks 4 and 12 (P < .01) in patients with and without PAD.
Conclusions
Subjects with PAD had elevated levels of matrix metalloproteinase-9, myeloperoxidase, interleukin-6, adiponectin, intercellular adhesion molecule-1, osteoprotegrin, CD40 ligand, high-sensitivity C-reactive protein, and triglycerides compared with those without PAD. Darapladib, a novel Lp-PLA2 inhibitor, was equally effective in reducing Lp-PLA2 activity levels in subjects with and without PAD.
doi:10.1016/j.ahj.2011.01.017
PMCID: PMC3750980  PMID: 21570531
2.  Centrifugation Speed Affects Light Transmission Aggregometry 
BACKGROUND
Light transmission aggregometry (LTA) is considered the gold-standard for investigating platelet activity ex vivo. However, LTA protocols are not standardized and differences in LTA procedure are a potential source of variance in results. Centrifugation speed is an essential component of platelet preparation in LTA, has yet to be standardized, and may affect platelet aggregation results. We sought to investigate the effect of relative centrifugal force (RCF) intensity on LTA results.
METHODS
Ten healthy controls had venous blood drawn and centrifuged at 150g, 200g, 300g, and 500g for 10 minutes. Cell counts in whole blood and PRP were measured using a hematology analyzer. LTA was performed using 1.0uM ADP and 0.4uM epinephrine as an agonist. Aggregation (%) was compared at 60, 120, 180, and 300 seconds (s) and at maximum aggregation.
RESULTS
Centrifugation speed was associated with decreasing platelet count (P<0.001) and decreasing MPV (P<0.001) in platelet rich plasma. Maximum aggregation decreased with increasing speeds for ADP 1.0uM (150g-89%, 200g-93%, 300g-71%, 500g-17%; P<0.001). Similar findings were noted at 120s (150g-69%, 200g-50%, 300g-35%, 500g-12%; P<0.001), 180s (150g-82%, 200g-74%, 300g-44%, 500g-13%; P<0.001), and 300s (150g-85%, 200g-88%, 300g-55%, 500g-14%; P<0.001). Consistently, platelet aggregation in response to epinephrine 0.4uM decreased significantly with increasing centrifuge RCF at 60s, 120s, 180s, 300s, and at maximum aggregation (P<0.05 for each comparison).
CONCLUSIONS
Our data demonstrate the importance of centrifugation speed in the interpretation of LTA results, supporting the need for standardization of centrifugation RCF in LTA protocols.
doi:10.1111/j.1751-553X.2011.01360.x
PMCID: PMC3209490  PMID: 21794095
Light transmission aggregometry; Methodology; Centrifuge; Platelets

Results 1-2 (2)