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1.  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
3.  Aspirin Use, Dose, and Clinical Outcomes in Postmenopausal Women with Stable Cardiovascular Disease: The Women’s Health Initiative Observational Study 
Background
Despite compelling evidence that aspirin reduces fatal and non-fatal vascular events among the overall population in various settings, women have frequently been underrepresented and their data underreported. We sought to evaluate the relationship between aspirin use, dose (81 or 325mg) and clinical outcomes among postmenopausal women with stable cardiovascular disease.
Methods
Women with cardiovascular disease (n=8928) enrolled in the Women’s Health Initiative Observational Study were used for this analysis. The primary outcome was the incidence of all-cause mortality and cardiovascular events (myocardial infarction, stroke and cardiovascular death).
Results
Among 8928 women with stable cardiovascular disease, 4101 (46%) reported taking aspirin, of whom 30% were on 81 and 70% were on 325mg. At 6.5 years of follow-up, no significant association was noted for aspirin use and all-cause mortality or cardiovascular events. However, after multivariate adjustment, aspirin use was associated with a significantly lower all-cause (adjusted HR 0.86, [0.75-0.99], P=0.04) and cardiovascular related mortality (adjusted HR 0.75, [0.60-0.95], P=0.01) compared with no aspirin. Aspirin use was associated with a lower risk of cardiovascular events (adjusted HR 0.90, [0.78-1.04], P=0.14) which did not meet statistical significance. Compared with 325mg, use of 81mg was not significantly different for all-cause mortality, cardiovascular events or any individual endpoint.
Conclusions
After multivariate adjustment, aspirin use was associated with significantly lower risk of all-cause mortality, specifically cardiovascular mortality, among postmenopausal women with stable cardiovascular disease. No significant difference was noted between 81 and 325mg of aspirin. Overall, aspirin use was low in this cohort of women with stable cardiovascular disease.
doi:10.1161/CIRCOUTCOMES.108.791269
PMCID: PMC2801891  PMID: 20031819
Aspirin; Dose; Women; Cardiovascular Disease; Observational Study
4.  Competency in Chest Radiography 
BACKGROUND
Accurate interpretation of chest radiographs (CXR) is essential as clinical decisions depend on readings.
OBJECTIVE
We sought to evaluate CXR interpretation ability at different levels of training and to determine factors associated with successful interpretation.
DESIGN
Ten CXR were selected from the teaching file of the internal medicine (IM) department. Participants were asked to record the most important diagnosis, their certainty in that diagnosis, interest in a pulmonary career and adequacy of CXR training. Two investigators independently scored each CXR on a scale of 0 to 2.
PARTICIPANTS
Participants (n = 145) from a single teaching hospital were third year medical students (MS) (n = 25), IM interns (n = 44), IM residents (n = 45), fellows from the divisions of cardiology and pulmonary/critical care (n = 16), and radiology residents (n = 15).
RESULTS
The median overall score was 11 of 20. An increased level of training was associated with overall score (MS 8, intern 10, IM resident 13, fellow 15, radiology resident 18, P<.001). Overall certainty was significantly correlated with overall score (r = .613, P<.001). Internal medicine interns and residents interested in a pulmonary career scored 14 of 20 while those not interested scored 11 (P = .027). Pneumothorax, misplaced central line, and pneumoperitoneum were diagnosed correctly 9%, 26%, and 46% of the time, respectively. Only 20 of 131 (15%) participants felt their CXR training sufficient.
CONCLUSION
We identified factors associated with successful CXR interpretation, including level of training, field of training, interest in a pulmonary career and overall certainty. Although interpretation improved with training, important diagnoses were missed.
doi:10.1111/j.1525-1497.2006.00427.x
PMCID: PMC1484801  PMID: 16704388
education; medical; radiography; thoracic; clinical competence; educational measurement

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