ALBERT

Description: Abstract 1179 Background Previous studies by our laboratory have demonstrated changes in apheresis collected, PLT concentrates during storage that are enhanced by Mirasol®PRT treatment. These include increased expression of P-selectin on PLTs and increased formation of neutrophil (PMN)/PLT aggregates. To explore the effect of these changes in a microvascular environment, we measured PLT adherence in a microfluidic chamber coated with collagen. Methods Three, double apheresis platelet products were collected from healthy volunteers with TRIMA system under an IRB approved protocol. One product of each pair was treated with Mirasol PRT and both were stored under standard conditions. Aliquots were sterilely removed from products during storage. To 1000 μl of fresh, ABO type specific, citrate anticoagulated whole blood was added 60 μl of apheresis platelet concentrate with or without PRT treatment on day 1 or 7 of storage and incubated for 5 min at 37C. The sample was recalcified with 20 mM CaCl2 and then pulled through the inlet of a microfluidic chamber at a flow sheer rate of 100 s−1. The flow chamber was composed of two parts, a glass slide patterned with collagen and a series of four polydimethylsiloxane microfluidic chambers per inlet. Stored PLTs were labeled with fluorescently labeled anti-CD41 to distinguish from PLTs of the whole blood. The chamber was mounted on an inverted fluorescence microscope, and video microscopic images sampled on observation field every 7 sec over 7 min. The number of fluorescent cells (stored PLTs) per field and the total area covered by all PLTs were determined at 7 min. Results The area, expressed as % of total field, covered by all of the PLTs in the sample was not different for whole blood alone (29 ± 3); Day 1 untreated (23 ± 9); Day 1 PRT treated (26 ± 8); Day 7 untreated (21 ± 5); and Day 7 treated (25 ± 9) PLTs. In contrast, there was an increase in the number of treated apheresis PLTs at Day 1 compared to untreated apheresis platelets binding to the chamber (2.26 ± 0.61 untreated, vs. 5.45 ± 1.45 treated, numbers are mean ± SEM for numbers of cells adhered normalized to the PLT count in the product, significant, p=0.0229). There was also an increase in binding of treated compared to untreated PLTs at Day 7 (2.43 ± 0.47 untreated, vs. 4.42 ± 1.35 treated). However, the results for untreated PLTs on Day 1 and 7 and treated PLTs on study days were not different. The increased binding of Mirasol PRT treated PLTs parallels the small decrease in recovery seen in clinical studies of patients receiving treated PLT concentrates compared to untreated products. Conclusion PRT treatment increases adherence of PLTs early in storage but does not appear to progress further. The changes may have implications for clinical responses to platelet transfusions. Evaluation of adherence in the microfluidic chamber provide a model which simulate the microvascular environment. Disclosures: Ambruso: Terumo BCT: Research Funding. Seewald:Terumo BCT: Research Funding. Marschner:Terumo BCT: Employment. Goodrich:Terumo BCT: Employment.

Description: Abstract 2288 Introduction Platelet concentrates develop biologically active compounds during storage which may play a role in adverse events of transfusion. Although many studies have focused on release of soluble pro-inflammatory compounds, changes in cells such as platelets may contribute to the response or pro-inflammatory effects of transfusion products. In previous studies we have shown that pathogen reduction with Mirasol PRT of apheresis PLT concentrates induced changes in PLTs which increased during storage including expression of P-selectin and the capacity to form PLT-PMN aggregates. These changes were also associated with increased adherence of stored PLTs in a microfluidic chamber. In the current study we evaluated P-selectin and PLT-PMN aggregate formation in whole blood after treatment with Mirasol PRT. Methods Ten units of whole blood from healthy donors were drawn into CPD under an IRB approved protocol. Five units where treated with Mirasol PRT and five units remained untreated. Aliquots were taken before and after treatment (or at same times for untreated units) on Day 0 and 24–27 hours after draw on Day 1 after storage at 22–24°C. Platelet rich plasma (PRP) was produced by standard technique and PLTs isolated on a Sepharose 2B column. PLTs were incubated with APC-CD62P and FITC-CD41a for comparison with P-selectin expressed as percent positive increase over isotype control. PMNs were isolated from 50 ml of heparinized peripheral blood drawn from healthy, ABO-matched donors. After a 5 min pre-incubation at 37°C in a shaking water bath, untreated, treated PLTs, and PMNs were incubated separately or together for 3 min then quenched at 4°C. FITC-CD41a and FITC-IgG1 isotype for platelet-PMN aggregate quantitation or PE-CD11b for CD11b expression on neutrophils were added. Platelet-PMN aggregates was expressed as percent of all PMN events above CD41a isotype control. CD11b expression was determined for PMNs after exposure to PLTs by flow cytometry. Results P-selectin positive cells did not change significantly over time in samples from untreated products (Table 1). After Mirasol PRT treatment, cells positive for P-selectin increased on Day 0 and 1 (p

Description: The biomarker composition of dissolved organic carbon (DOC) of the six largest Arctic rivers was studied between 2003 and 2007 as part of the PARTNERS Project. Samples were collected over seasonal cycles relatively close to the river mouths. Here we report the lignin phenol and p-hydroxybenzene composition of Arctic river DOC in order to identify major sources of carbon. Arctic river DOC represents an important carbon conduit linking the large pools of organic carbon in the Arctic/Subarctic watersheds to the Arctic Ocean. Most of the annual lignin discharge (〉75%) occurs during the two month of spring freshet with extremely high lignin concentrations and a lignin phenol composition indicative of fresh vegetation from boreal forests. The three large Siberian rivers, Lena, Yenisei, and Ob, which also have the highest proportion of forests within their watersheds, contribute about 90% of the total lignin discharge to the Arctic Ocean. The composition of river DOC is also characterized by elevated levels of p-hydroxybenzenes, particularly during the low flow season, which indicates a larger contribution from mosses and peat bogs. The lignin composition was strongly related to the average 14C-age of DOC supporting the abundance of young, boreal-vegetation-derived leachates during spring flood, and older, soil-, peat-, and wetland-derived DOC during groundwater dominated low flow conditions, particularly in the Ob and Yukon Rivers. We observed significant differences in DOC concentration and composition between the rivers over the seasonal cycles with the Mackenzie River being the most unique, the Lena River being similar to the Yenisei, and the Yukon being most similar to the Ob. The observed relationship between the lignin phenol composition and watershed characteristics suggests that DOC discharge from these rivers could increase in a warmer climate under otherwise undisturbed conditions.