Induced forms of α2-macroglobulin neutralize heparin and direct oral anticoagulant effects.

Alpha2-macroglobulin (α2M) is a physiological macromolecule that facilitates the clearance of many proteinases, cytokines and growth factors in human. Here, we explored the effect of induced forms of α2M on anticoagulant drugs. Gla-domainless factor Xa (GDFXa) and methylamine (MA)-induced α2M were prepared and characterized by electrophoresis, immunonephelometry, chromogenic, clot waveform and rotational thromboelastometry assays. Samples from healthy volunteers and anticoagulated patients were included. In vivo neutralization of anticoagulants was evaluated in C57Bl/6JRj mouse bleeding-model. Anticoagulant binding sites on induced α2M were depicted by computer-aided energy minimization modeling. GDFXa-induced α2M neutralized dabigatran and heparins in plasma and whole blood. In mice, a single IV dose of GDFXa-induced α2M following anticoagulant administration significantly reduced blood loss and bleeding time. Being far easier to prepare, we investigated the efficacy of MA-induced α2M. It neutralized rivaroxaban, apixaban, dabigatran and heparins in spiked samples in a concentration-dependent manner and in samples from treated patients. Molecular docking analysis evidenced the ability of MA-induced α2M to bind non-covalently these compounds via some deeply buried binding sites. Induced forms of α2M have the potential to neutralize direct oral anticoagulants and heparins, and might be developed as a universal antidote in case of major bleeding or urgent surgery.

Modified ROTEM for the detection of rivaroxaban and apixaban anticoagulant activity in whole blood: A diagnostic test study.

BACKGROUND: Rapid detection of the anticoagulant effect of oral factor Xa (FXa) inhibitors may be essential in several emergency clinical situations. Specific assays quantifying the drugs are performed in plasma and require a turnaround time that is too long to be useful in emergency situations. Rotational thromboelastometry (ROTEM) is a whole blood coagulation assay of blood viscoelasticity and could be of interest for FXa inhibitor detection in emergency. However, conventional ROTEM reagents only detect high amounts of inhibitors. OBJECTIVE: The aim of this study was first to assess the effect of whole blood components on the viscoelastic measurement of the effects of FXa inhibitors, and second to evaluate whether a modified ROTEM, triggered with a low amount of tissue factor and a saturating amount of phospholipid vesicles, can reliably detect low levels of FXa inhibitor activity in whole blood. DESIGN: Diagnostic test study. SETTINGS: A university research laboratory. From November 2014 to April 2016. PATIENTS: Sixty-six patients: 30 treated with rivaroxaban, 17 with apixaban and 19 without treatment. INTERVENTION: ROTEM was triggered with 2.5 pmol l of tissue factor and 10 µmol l of phospholipid vesicles. MAIN OUTCOME MEASURES: Modified ROTEM parameters were measured in different experimental conditions: platelet-poor plasma (PPP), platelet-rich plasma, PPP supplemented with fibrinogen and reconstituted whole blood with various haematocrit levels adjusted between 30 and 60%. Modified ROTEM was further validated using whole blood from patients who were either treated or not treated with FXa inhibitors. RESULTS: Modified ROTEM allowed detection of as little as 25 ng ml FXa inhibitors in PPP, with at least a 1.4-fold increase of the clotting time (P ≤ 0.02). Neither changes of fibrinogen concentration nor variations of platelet count or haematocrit precluded FXa inhibitor detection. A lengthened modified ROTEM clotting time of more than 197 s allowed detection of FXa inhibitor concentrations above 30 ng ml in whole blood with 90% sensitivity and 85% specificity. CONCLUSION: Modified ROTEM may be applicable in emergency situations for the detection of FXa inhibitors in whole blood.

Vitamin K antagonists and emergencies.

The recent emergence of 'non-VKA' oral anticoagulants may have led to some forgetting that vitamin K antagonists (VKA) are by far the most widely prescribed oral anticoagulants worldwide. Consequently, we decided to summarize the information available on them. This paper presents the problems facing emergency physicians confronted with patients on VKAs in 10 points, from pharmacological data to emergency management. Vitamin K antagonists remain preferable in many situations including in the elderly, in patients with extreme body weights, severe chronic kidney or liver disease or valvular heart disease, and in patients taking VKAs with well-controlled international normalized ratios (INRs). Given the way VKAs work, a stable anticoagulant state can only be achieved at the earliest 5 days after starting therapy. The induction phase of VKA treatment is associated with the highest risk of bleeding; validated algorithms based on INR values have to be followed. VKA asymptomatic overdoses and 'non-severe' hemorrhage are managed by omitting a dose or stopping treatment plus administering vitamin K depending on the INR. Major bleeding is managed using a VKA reversal strategy. A prothrombin complex concentrate infusion plus vitamin K is preferred to rapidly achieve an INR of up to 1.5 and maintain a normal coagulation profile. The INR must be measured 30 min after the infusion. Before an invasive procedure, if an INR of less than 1.5 (<1.3 in neurosurgery) is required, it can be achieved by combining prothrombin complex concentrate and vitamin K. A well-codified strategy is essential for managing patients requiring emergency invasive procedures or presenting bleeding complications.

A retrospective comparison between delayed and early hip fracture surgery in patients taking clopidogrel: same total bleeding but different timing of blood transfusion.

PURPOSE: Managing hip fracture surgery in patients taking clopidogrel is challenging. The optimal timing for surgery remains unclear. Early surgery in such patients potentially increases peri-operative bleeding, whereas delayed surgery has been shown to be associated with worse postoperative outcomes. The aim of this study was to investigate whether a delay to surgery affects total blood loss, bleeding kinetics, blood transfusion requirements, or post-operative outcomes. METHODS: A retrospective monocentric study including all hip fracture patients treated with clopidogrel between 2011 and 2016 (39 patients) was carried out. Patients who underwent delayed surgery after withholding clopidogrel for five days or more, from 2011 to 2013, were compared to patients who benefited from earlier surgical procedures (within 48 hours of admission) from 2014 to 2016. RESULTS: Total blood loss, amount of blood transfusion and rate of postoperative complications did not differ between the two groups. However, the timing of bleeding was significantly different; blood loss occurred during the pre-operative phase in the delayed surgery group (p < 0.0001), whereas it occurred during the intra-operative phase in the early surgery group (p = 0.005). The length of the hospital stay was significantly shorter for the early surgery group than for the delayed surgery group: 11 ± three versus 15 ± four days (p = 0.004). CONCLUSIONS: Early surgical treatment of hip fracture in patients receiving clopidogrel does not increase the overall red blood cell loss or the transfusion requirement, but may affect the timing of blood transfusion. Hip fracture surgery should preferably be performed without delay in patients taking clopidogrel.

Use of near-infrared spectroscopy in predicting response to intravenous fluid load in anaesthetized infants.

INTRODUCTION: The prediction of fluid responsiveness in paediatrics and infants remains problematic. We sought to test the validity of the measurement of StcO2 as a predictive parameter of fluid responsiveness in infants less than one year old during non-cardiac surgery. MATERIALS AND METHODS: This was a prospective observational study on infants aged less than 1 year without any cardiac disease during the intraoperative period of non-cardiac surgery. Cerebral oxygen saturation (StcO2) was obtained using infrared spectroscopic INVOS® monitors. Reference values were obtained 10 minutes after intubation. Fluid load indications were dependent on the anaesthesiologist caring for the patient. The objective of this study was to determine the accuracy of StcO2 values before vascular filling (StcO2B) and the difference in StcO2 values between the reference value and before vascular filling (ΔStcO2), in predicting vascular filling response defined as an increase in mean arterial pressure over 15%. Statistical analysis was carried out using ROC curve analysis with determination of grey zones. RESULTS: Twenty-nine patients were eligible for this study, 23 were included in the study (one intravenous fluid challenge per patient). There were 10 responders and 13 non-responders. The StcO2B and the ΔStcO2 were significantly different between responders and non-responders. Analysis of the ROC curve found an area under the curve of 0.75 [95% CI 0.56 to 0.95] for StcO2B and 0.83 [95% CI 0.66 to 0.99] for ΔStcO2. The grey-areas were [59-78] and [16-28] for StcO2B and ΔStcO2. CONCLUSION: NIRS appears to be an interesting additional tool for predicting an increase of blood pressure in response to intraoperative fluid challenge in infants less than one year old.

An immunosurveillance mechanism controls cancer cell ploidy.

Cancer cells accommodate multiple genetic and epigenetic alterations that initially activate intrinsic (cell-autonomous) and extrinsic (immune-mediated) oncosuppressive mechanisms. Only once these barriers to oncogenesis have been overcome can malignant growth proceed unrestrained. Tetraploidization can contribute to oncogenesis because hyperploid cells are genomically unstable. We report that hyperploid cancer cells become immunogenic because of a constitutive endoplasmic reticulum stress response resulting in the aberrant cell surface exposure of calreticulin. Hyperploid, calreticulin-exposing cancer cells readily proliferated in immunodeficient mice and conserved their increased DNA content. In contrast, hyperploid cells injected into immunocompetent mice generated tumors only after a delay, and such tumors exhibited reduced DNA content, endoplasmic reticulum stress, and calreticulin exposure. Our results unveil an immunosurveillance system that imposes immunoselection against hyperploidy in carcinogen- and oncogene-induced cancers.

Prognostic impact of vitamin B6 metabolism in lung cancer.

Patients with non-small cell lung cancer (NSCLC) are routinely treated with cytotoxic agents such as cisplatin. Through a genome-wide siRNA-based screen, we identified vitamin B6 metabolism as a central regulator of cisplatin responses in vitro and in vivo. By aggravating a bioenergetic catastrophe that involves the depletion of intracellular glutathione, vitamin B6 exacerbates cisplatin-mediated DNA damage, thus sensitizing a large panel of cancer cell lines to apoptosis. Moreover, vitamin B6 sensitizes cancer cells to apoptosis induction by distinct types of physical and chemical stress, including multiple chemotherapeutics. This effect requires pyridoxal kinase (PDXK), the enzyme that generates the bioactive form of vitamin B6. In line with a general role of vitamin B6 in stress responses, low PDXK expression levels were found to be associated with poor disease outcome in two independent cohorts of patients with NSCLC. These results indicate that PDXK expression levels constitute a biomarker for risk stratification among patients with NSCLC.