Sample fixation for storage and/or transportation represents an unsolved challenge for multicenter clinical trials assessing serial changes in platelet activity, or monitoring various antiplatelet regimens. Whole blood flow cytometry represents a major advance in defining platelet function, although special training and expensive equipment is required. We sought to determine how fixation with 2% paraformaldehyde (PFA), and storage of blood samples over 1 week affects the flow cytometry readings for both intact and thrombin-activating four major surface platelet receptors. Whole blood platelet expression of PECAM-1, P-selectin, PAR-1 inactive receptor (SPAN-12), and cleaved (WEDE-15) epitope was assessed immediately after blood draw, after staining with 2% PFA, and at day 1, 3, 5, and 7. The study was performed in 6 volunteers with multiple risk factors for vascular disease, not receiving any antiplatelet agents. Staining with PFA resulted in a slight decrease of fluorescence intensity, especially for PECAM-1, while antigen expression at day 1, 3 and 5 remains consistent, and highly reproducible. At day 7 there was a small but inconsistent trend towards diminished fluorescence intensity. The platelet data were consistent while validated with the isotype-matched irrelevant antibody. These data suggest that there is a 5 day window to perform final flow cytometry readings of whole blood PFA-fixed inactivated platelet samples. In contrast, thrombin activation cause gradual loss of flow cytometry signal, and cannot be recommended for long-term storage. This is critical logistic information for conducting multicenter platelet substudies within the framework of major clinical trials.

Extended release dipyridamole (ERD) is widely used in patients after ischaemic stroke; however, the ability of this antithrombotic agent to be stored in different blood cells has never been explored in post-stroke patients. We hypothesised that since ERD is known to be highly lipophilic, the drug may be present not only in plasma, but also accumulated in platelets, leukocytes, and erythrocytes. Fifteen patients after documented ischaemic stroke were treated with Aggrenox (ERD and low-dose aspirin combination) BID for 30 days, and 12 of them completed the study. ERD concentrations in blood cells and platelet-poor plasma were measured by spectrofluorimetry at Baseline, Day 14, and Day 30 after the initiation of therapy. The background level of spectrofluorometry readings differs slightly among the blood components (132-211 ng/ml) due to the differences in the preparation of samples and cell isolation techniques. As expected, two weeks of ERD therapy produced steady-state plasma concentration of dipyridamole already at Day 14 (1,680 +/- 542 ng/ ml), followed by a slight not significant decrease at one month (1,619 +/- 408 ng/ml). Two weeks of therapy was sufficient to achieve a consistent dipyridamole accumulation in erythrocytes (361 +/- 43 ng/ml), but not in platelets (244 +/- 78 ng/ml), or leukocytes (275 +/- 49 ng/ml). In fact, white blood cells continued dipyridamole intake beyond 14 days period, and this increase (398 +/- 66 ng/ml) was significant (p = 0.02) at 30 days. Treatment with ERD in post-stroke patients resulted not only in achievement of therapeutic plasma dipyridamole concentrations, but also deposition of the drug in erythrocytes and leukocytes, but not in platelets. If confirmed, these data will affect our better understanding of dipyridamole pleiotropy, and may explain long-term benefit of ERD formulation.

SUMMARY -Aicardi syndrome (AS) is defined by the triad of corpus callosum agenesis

We describe a case of an 11-month-old baby presenting to the emergency room with a foreign body in the upper airway. After unsuccessfully attempting to remove the foreign body in the emergency department, the otolaryngologist was consulted. The patient was taken to the operating room, and a comb was successfully removed under conscious sedation. This case illustrates the need of a well-considered strategy for managing the airway of a pediatric patient with a foreign body, while also demonstrating the unique challenges of treating pediatric patients.