For the past three years, we have routinely used the one‐hour in vivo survival of 51Cr‐labeled donor red blood cells to select units for transfusion to patients for whom crossmatch compatible blood was unavailable. This technique successfully evaluated in vivo compatibility, thus avoiding acute hemolytic transfusion reactions in 38 problem patients. New or confirmatory data regarding the hemolytic potential of several well defined antibodies was also obtained. Antibodies which proved to be clinically insignificant included: anti‐IT (all IgG), anti‐Sda, anti‐Kir, Mil, Oca, anti‐Chido, anti‐Bg, 14 of 15 “nonspecific warm autoantibodies” (three of which were associated with the ingestion of alphamethyldopa), and four of five antibodies to high‐incidence antigens. Clinically significant antibodies included: anti‐Yta, anti‐Jkb, the antibody in PCH (with “P” specificity), one intensely hemolytic “nonspecific warm autoagglutinin,” and one of five incompletely characterized antibodies to high‐incidence antigens. An acceptable in vivo compatibility test in every instance was associated with an appropriate rise in hematocrit and no clinical symptoms of hemolytic transfusion reaction.

The classic assumption that a large fraction of blood creatinine remains sequestered within erythrocytes when blood is dialyzed has been challenged by recent observations where approximately 60% of erythrocyte water appeared accessible to diffusive creatinine transport during a dialyzer transit. This discrepancy provided the motivation to revisit and reanalyze the equilibration of creatinine across the erythrocyte membrane in a series of in vitro studies with normal human blood under erythrocyte loading and unloading conditions at 37 degrees C. The time course of plasma creatinine concentrations measured by a kinetic picric acid assay was analyzed using a 2-compartment model. In 7 experiments, the equilibration constant was 0.052 +/- 0.013/min, corresponding to a mean half-life of 13.8 +/- 2.8 minutes, and comparable for erythrocyte loading and unloading. With these values and with mean dialyzer transit times in the range of 20 seconds the fraction of erythrocyte water accessible to diffusive clearance is in the range of 2%. These results are comparable to what has been measured with radiolabeled markers almost half a century ago. Therefore, when dialyzer outlet concentrations are sampled without equilibration the effective diffusion volume flow rate for creatinine is close to plasma water flow and does not include sizeable fractions of erythrocyte water flow.

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Atherosclerosis (AS) is one of the leading causes of mortality in high-income countries. Early diagnosis of vulnerable atherosclerotic lesions is one of the biggest challenges currently facing cardiovascular medicine. The present study focuses on developing targeted nanoparticles (NPs) in order to improve the detection of vulnerable atherosclerotic-plaques. Various biomarkers involved in the pathogenesis of atherosclerotic-plaques have been identified and one of these promising candidates for diagnostic targeting is interleukin 10 (IL10). IL10 has been shown to be a key anti-inflammatory responding cytokine in the early stages of atherogenesis, and has already been used for therapeutic interventions in humans and mice. IL10, the targeting sequence, was coupled to two different types of NPs: protamine-oligonucleotide NPs (proticles) and sterically stabilized liposomes in order to address the question of whether the recognition and detection of atherosclerotic-lesions is primarily determined by the targeting sequence itself, or whether it depends on the NP carrier system to which the biomarker is coupled. Each IL10-targeted NP was assessed based on its sensitivity and selectivity toward characterizing atherosclerotic-plaque lesions using an apolipoprotein E-deficient mouse as the model of atherosclerosis. Aortas from apolipoprotein E-deficient mice fed a high fat diet, were stained with either fluorescence-labeled IL10 or IL10-coupled NPs. Ex vivo imaging was performed using confocal laser-scanning microscopy. We found that IL10-targeted proticles generated a stronger signal by accumulating at the surface of atherosclerotic-plaques, while IL10-targeted, sterically stabilized liposomes showed a staining pattern deeper in the plaque compared to the fluorescence-labeled IL10 alone. Our results point to a promising route for enhanced in vivo imaging using IL10-targeted NPs. NPs allow a higher payload of signal emitting molecules to be delivered to the atherosclerotic-plaques, thus improving signal detection. Importantly, this allows for the opportunity to visualize different areas within the plaque scenario, depending on the nature of the applied nanocarrier.