Pb(II) Induces Scramblase Activation and Ceramide-Domain Generation in Red Blood Cells

The mechanisms of Pb(II) toxicity have been studied in human red blood cells using confocal microscopy, immunolabeling, fluorescence-activated cell sorting and atomic force microscopy. The process follows a sequence of events, starting with calcium entry, followed by potassium release, morphological change, generation of ceramide, lipid flip-flop and finally cell lysis. Clotrimazole blocks potassium channels and the whole process is inhibited. Immunolabeling reveals the generation of ceramide-enriched domains linked to a cell morphological change, while the use of a neutral sphingomyelinase inhibitor greatly delays the process after the morphological change, and lipid flip-flop is significantly reduced. These facts point to three major checkpoints in the process: first the upstream exchange of calcium and potassium, then ceramide domain formation, and finally the downstream scramblase activation necessary for cell lysis. In addition, partial non-cytotoxic cholesterol depletion of red blood cells accelerates the process as the morphological change occurs faster. Cholesterol could have a role in modulating the properties of the ceramide-enriched domains. This work is relevant in the context of cell death, heavy metal toxicity and sphingolipid signaling.AGA was a predoctoral student supported by the Basque Government and later by the University of the Basque Country (UPV/EHU). This work was also supported in part by grants from the Spanish Government (FEDER/MINECO BFU 2015-66306-P to F.M.G. and A.A.) and the Basque Government (IT849-13 to F.M.G. and IT838-13 to A.A.), and by the Swiss National Science Foundation

Cerebro-spinal fluid glucose and lactate concentrations changes in response to therapies in patIents with primary brain injury: the START-TRIP study

Introduction: Altered levels of cerebrospinal fluid (CSF) glucose and lactate concentrations are associated with poor outcomes in acute brain injury patients. However, no data on changes in such metabolites consequently to therapeutic interventions are available. The aim of the study was to assess CSF glucose-to-lactate ratio (CGLR) changes related to therapies aimed at reducing intracranial pressure (ICP). Methods: A multicentric prospective cohort study was conducted in 12 intensive care units (ICUs) from September 2017 to March 2022. Adult (> 18 years) patients admitted after an acute brain injury were included if an external ventricular drain (EVD) for intracranial pressure (ICP) monitoring was inserted within 24 h of admission. During the first 48–72 h from admission, CGLR was measured before and 2 h after any intervention aiming to reduce ICP (“intervention”). Patients with normal ICP were also sampled at the same time points and served as the “control” group. Results: A total of 219 patients were included. In the intervention group (n = 115, 53%), ICP significantly decreased and CPP increased. After 2 h from the intervention, CGLR rose in both the intervention and control groups, although the magnitude was higher in the intervention than in the control group (20.2% vs 1.6%; p = 0.001). In a linear regression model adjusted for several confounders, therapies to manage ICP were independently associated with changes in CGLR. There was a weak inverse correlation between changes in ICP and CGRL in the intervention group. Conclusions: In this study, CGLR significantly changed over time, regardless of the study group. However, these effects were more significant in those patients receiving interventions to reduce ICP

Plasma transfusion in the intensive care unit

Background: Current guidelines discourage prophylactic plasma use in non‐bleeding patients. This study assesses global plasma transfusion practices in the intensive care unit (ICU) and their alignment with current guidelines. Study Design and Methods: This was a sub‐study of an international, prospective, observational cohort. Primary outcomes were in‐ICU occurrence rate of plasma transfusion, proportion of plasma events of total blood products events, and number of plasma units per event. Secondary outcomes included transfusion indications, INR/PT, and proportion of events for non‐bleeding indications. Results: Of 3643 patients included, 356 patients (10%) experienced 547 plasma transfusion events, accounting for 18% of total transfusion events. A median of 2 (IQR 1, 2) units was given per event excluding massive transfusion protocol (MTP) and 3 (IQR 2, 6) when MTP was activated. MTP accounted for 39 (7%) of events. Indications of non‐MTP events included active bleeding (54%), prophylactic (25%), and pre‐procedure (12%). Target INR/PT was stated for 43% of transfusion events; pre‐transfusion INR/PT or visco‐elastic hemostatic assays (VHA) were reported for 73%. Thirty‐seven percent of events were administered for non‐bleeding indications, 54% with a pre‐transfusion INR < 3.0 and 30% with an INR < 1.5. Discussion: Plasma transfusions occurred in 10% of ICU patients. Over a third were given for non‐bleeding indications and might have been avoidable. Target INR/PT was not stated in more than half of transfusions, and pre‐transfusion INR/PT or VHA was not reported for 27%. Further research and education is needed to optimize guideline implementation and to identify appropriate indications for plasma transfusion

Global transfusion practices in septic patients in the intensive care unit: insights from the InPUT ‐study sub‐analysis

Background: Transfusion practices among intensive care unit (ICU) patients with sepsis vary widely. While restrictive hemoglobin thresholds for red blood cell (RBC) transfusion are well studied, the indications and thresholds for platelet and plasma transfusions remain uncertain. Methods: We performed a sepsis‐specific sub‐analysis of the International Point Prevalence Study of Intensive Care Unit Transfusion Practices, a prospective, multicenter, observational study capturing all adult ICU admissions during four pre‐scheduled weeks between March 2019 and October 2022. Patients admitted with sepsis or septic shock, or who developed sepsis during their ICU stay, were included. We recorded demographics, daily laboratory values, and transfusion triggers. Primary endpoints were the proportions of patients receiving RBCs, platelets, or plasma; secondary endpoints were indications, pre‐transfusion thresholds, and blood loss. Results: Among 3643 screened patients, 799 (22%) fulfilled sepsis criteria; within this subgroup, 317 (40%) received at least one blood component. RBCs were transfused in 269 patients (34%), primarily to address anemia or hemodynamic instability, at a mean pre‐transfusion hemoglobin of 7.5 ± 1.4 g/dL, consistent with restrictive practice. Platelets were given to 78 patients (10%) for prophylaxis or active bleeding at a median count of 26 × 109 cells/L (interquartile range 16–51 × 109 cells/L). Plasma was administered to 108 patients (14%), half for bleeding control and half for non‐bleeding indications. Conclusions: This largest international snapshot of septic ICU transfusion practices confirms adherence to restrictive RBC thresholds but reveals substantial variability in platelet and plasma use. These findings underscore the need for targeted trials to refine transfusion guidelines in sepsis