Spleen dysfunction is central to morbidity and mortality in children with sickle cell anemia (SCA). The initiation and determinants of spleen injury, including acute splenic sequestration (ASS) have not been established. We investigated splenic function longitudinally in a cohort of 57 infants with SCA enrolled at 3 to 6 months of age and followed up to 24 months of age and explored the respective contribution of decreased red blood cell (RBC) deformability and increased RBC adhesion on splenic injury, including ASS. Spleen function was evaluated by sequential 99mTc heated RBC spleen scintigraphy and high-throughput quantification of RBCs with Howell-Jolly bodies (HJBs). At 6 and 18 months of age, spleen filtration function was decreased in 32% and 50% of infants, respectively, whereas the median %HJB-RBCs rose significantly (from 0.3% to 0.74%). An excellent correlation was established between %HJB-RBCs and spleen scintigraphy results. RBC adhesion to laminin and endothelial cells increased with time. Adhesion to endothelial cells negatively correlated with splenic function. Irreversibly sickled cells (ISCs), used as a surrogate marker of impaired deformability, were detected at enrollment and increased significantly at 18 months. %ISCs correlated positively with %HJB-RBCs and negatively with splenic uptake, indicating a relationship between their presence in the circulation and spleen dysfunction. In the subgroup of 8 infants who subsequently experienced ASS, %ISCs at enrollment were significantly higher compared with the asymptomatic group, suggesting a major role of impaired deformability in ASS. Higher levels of %HJB-RBCs were observed after the occurrence of ASS, demonstrating its negative impact on splenic function.

Some proteolytic enzymes are able to increase reversibly the permeability of the blood-brain barrier (BBB) to different tracers such as trypan blue. Intraventricularly injected collagenase is the most potent of the enzymes tested. It was assumed that collagenase acts on basement membrane collagen, the partial hydrolysis of which increases BBB permeability, and that the recovery of normal permeability requires resynthesis of the degraded substrate. In this paper, it is shown that injection of collagenase in lateral brain ventricles of rats increases the level of hydroxyproline (hypro) in the CSF, suggesting that collagen is indeed degraded by the enzyme. We also demonstrate that treatment with inhibitors of protein synthesis-puromycin and cycloheximide-delays considerably the recovery of normal BBB permeability, which occurs 140 h after collagenase treatment instead of 70-72 h without inhibitors. This fact indicates that protein synthesis is necessary for the recovery of normal BBB permeability. The demonstration of release of hypro in the cerebrospinal fluid (CSF) after collagenase action, and of the necessity of protein synthesis for the recovery of normal permeability, supports the above-mentioned hypothesis, according to which basement membrane collagen plays a role in the regulation of the permeability of the BBB.

BackgroundThe optimal control of blood volume without fluid overload is a main challenge in the daily care of intensive care unit (ICU) patients. Accordingly this study focused on the identification of biomarkers to help characterize fluid overload status.MethodsSixty-seven patients were studied from ICU admission to day 7 (D7). Blood and urine samples were taken daily and sodium and water balance strictly calculated resulting in a total cumulative assessment of ∆Na+ and ∆H2O. Furthermore, plasmatic biomarkers (cortisol, epinephrine, norepinephrine, renin, angiotensin II, aldosterone, pro-endothelin, copeptine, atrial natriuretic peptide, erythropoietin, mid-regional pro-adrenomedullin (MR-proADM)) and Sequential Organ Failure Assessment (SOFA) scores were measured at D2, D5 and D7. Blood volumes were measured with 51Cr fixed on red blood cells at D2 and D7.ResultsThe ∆Na+ or ∆H2O were increased in all patients but never related to blood volumes at D2 nor D7. Total blood volumes were at normal values with constantly low red blood cell volumes and normal or decreased plasmatic volume. Weight, plasmatic proteins, and hemoglobin were weakly related to ∆Na+ or ∆H2O. Amongst all tested biomarkers, only MR-proADM was related to sodium and fluid overload. This biomarker was also a predictor of SOFA scores.ConclusionsPlasmatic concentration in MR-proADM seems to be a good surrogate for evaluation of ∆Na+ or ∆H2O and predicts sodium and extracellular fluid overload.Trial registrationClinicalTrials.gov: NCT01858675 in May 13, 2013.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1540-x) contains supplementary material, which is available to authorized users.

The goal of this study was to quantify in the dog the error that is made in assessing drug tissue concentrations when no correction for blood contamination is performed and hence to determine in which organs such a correction should be made. The organs investigated were the heart, the brain, the liver and the skeletal muscle, and the test drug used was the H1-antihistamine, cetirizine (0.1 or 0.6 mg/kg/day for 3 days, orally, n = 6 dogs). Radiolabelled serum albumin was used to quantitate blood trapped in the tissues. Blood and tissue samplings were performed 2 h after the last drug administration. Mean (+/-SEM) volumes of blood trapped in the liver, heart, muscle and brain were 263 +/- 12, 91 +/- 3, 27 +/- 1 and 20 +/- 2 microL/g, respectively. Apparent tissue/blood concentration ratios of cetirizine were 2.39 +/- 0.33, 1.11 +/- 0.09, 0.77 +/- 0.07 and 0.37 +/- 0.05 in the four organs. When correction for residual blood is not performed, cetirizine concentrations are underestimated (-13.6 +/- 3.2%) in the liver, slightly overestimated (+4.7 +/- 1.5 to +6.3 +/- 2.8%) in the brain, and neither over nor underestimated in the heart and muscle. Simulation data over a wide range of theoretical drug tissue/blood concentration ratios indicate that in the dog: (a) for the liver, correction of apparent tissue concentration for residual blood should be performed when the drug tissue/blood concentration ratio achieved is <0.8 or >4, (b) for the heart, correction should be made when this ratio is < or =0.4 and (c) for the brain and muscle, no correction is necessary unless the ratio is < or =0.1.