Delayed Leukoreduction of whole blood with a platelet-sparing filter to increase low-titer group O whole blood production in the United States.

BACKGROUND: Demand for low-titer Group O whole blood (LTOWB) is increasing for trauma. The whole blood (WB) platelet-sparing (WB-SP) filter enables leukoreduction (LR) while retaining platelet quantity and function; however, in the United States WB must be filtered and placed in the cold within 8 h of collection. A longer processing window would facilitate improved logistics and supply of LR-WB to meet the growing medical need. This study evaluated the impact of increasing filtration timing from <8 h to <12 h on the quality of LR-WB. STUDY DESIGN AND METHODS: Thirty WB units were collected from healthy donors. Control units were filtered within 8 h and test units within 12 h of collection. WB was tested throughout 21 days of storage. Hemolysis, WBC content, component recovery, and 25 additional markers of WB quality were tested including hematologic and metabolic markers, RBC morphology, aggregometry, thromboelastography, and p-selectin. RESULTS: There were 0 failures for residual WBC content, hemolysis, or pH, and no differences in component recovery between arms. Few differences in metabolic parameters were observed, but the small effect size suggests these are not clinically significant. Trends throughout storage were similar and filtration timing did not impact hematological parameters, platelet activation and aggregation, or hemostatic capacity. CONCLUSION: Our studies showed that extending filtration timing from 8 to 12 h from the collection does not significantly impact the quality of LR-WB. Characterization of the platelets demonstrated that storage lesions were not exacerbated. Extending the time from collection to filtration will improve LTOWB inventory in the United States.

Gene Duplication in Pseudomonas aeruginosa Improves Growth on Adenosine.

The laboratory strain of Pseudomonas aeruginosa, PAO1, activates genes for catabolism of adenosine using quorum sensing (QS). However, this strain is not well-adapted for growth on adenosine, with doubling times greater than 40 h. We previously showed that when PAO1 is grown on adenosine and casein, variants emerge that grow rapidly on adenosine. To understand the mechanism by which this adaptation occurs, we performed whole-genome sequencing of five isolates evolved for rapid growth on adenosine. All five genomes had a gene duplication-amplification (GDA) event covering several genes, including the quorum-regulated nucleoside hydrolase gene, nuh, and PA0148, encoding an adenine deaminase. In addition, two of the growth variants also exhibited a nuh promoter mutation. We recapitulated the rapid growth phenotype with a plasmid containing six genes common to all the GDA events. We also showed that nuh and PA0148, the two genes at either end of the common GDA, were sufficient to confer rapid growth on adenosine. Additionally, we demonstrated that the variant nuh promoter increased basal expression of nuh but maintained its QS regulation. Therefore, GDA in P. aeruginosa confers the ability to grow efficiently on adenosine while maintaining QS regulation of nucleoside catabolism.IMPORTANCEPseudomonas aeruginosa thrives in many habitats and is an opportunistic pathogen of humans. In these diverse environments, P. aeruginosa must adapt to use myriad potential carbon sources. P. aeruginosa PAO1 cannot grow efficiently on nucleosides, including adenosine; however, it can acquire this ability through genetic adaptation. We show that the mechanism of adaptation is by amplification of a specific region of the genome and that the amplification preserves the regulation of the adenosine catabolic pathway by quorum sensing. These results demonstrate an underexplored mechanism of adaptation by P. aeruginosa, with implications for phenotypes such as development of antibiotic resistance.