Metabolic profile distinguishes laminitis-susceptible and -resistant ponies before and after feeding a high sugar diet

Background Insulin dysregulation (ID) is a key risk factor for equine endocrinopathic laminitis, but in many cases ID can only be assessed accurately using dynamic tests. The identification of other biomarkers could provide an alternative or adjunct diagnostic method, to allow early intervention before laminitis develops. The present study characterised the metabolome of ponies with varying degrees of ID using basal and postprandial plasma samples obtained during a previous study, which examined the predictive power of blood insulin levels for the development of laminitis, in ponies fed a high-sugar diet. Samples from 10 pre-laminitic (PL – subsequently developed laminitis) and 10 non-laminitic (NL – did not develop laminitis) ponies were used in a targeted metabolomic assay. Differential concentration and pathway analysis were performed using linear models and global tests. Results Significant changes in the concentration of six glycerophospholipids (adj. P ≤ 0.024) and a global enrichment of the glucose-alanine cycle (adj. P = 0.048) were found to characterise the response of PL ponies to the high-sugar diet. In contrast, the metabolites showed no significant association with the presence or absence of pituitary pars intermedia dysfunction in all ponies. Conclusions The present results suggest that ID and laminitis risk are associated with alterations in the glycerophospholipid and glucose metabolism, which may help understand and explain some molecular processes causing or resulting from these conditions. The prognostic value of the identified biomarkers for laminitis remains to be investigated in further metabolomic trials in horses and ponies.

Insights into the Procoagulant Profile of Patients with Systemic Lupus Erythematosus without Antiphospholipid Antibodies

We aimed to identify the key players in the prothrombotic profile of patients with systemic lupus erythematosus (SLE) not mediated by antiphospholipid antibodies, as well as the potential utility of global coagulation tests to characterize hemostasis in these patients. Patients with SLE without antiphospholipid antibodies and without signs of thrombosis were included. The kinetics of clot formation were determined by ROTEM®. Platelet activation markers were determined by flow cytometry. Thrombin generation associated with Neutrophil Extracellular Traps (NETs) and microparticles (MPs) was measured by calibrated automated thrombogram (CAT). The plasma levels of PAI-1 were also determined. ROTEM® showed a procoagulant profile in SLE patients. SLE patients had activated platelets and more leukocyte/platelet aggregates at basal conditions. The plasma PAI-1 and platelet aggregates correlated with several ROTEM® parameters. The thrombin generation associated withthe tissue factor (TF) content of MPs and with NETs was increased. Our results suggest the utility of global tests for studying hemostasis in SLE patients because they detect their procoagulant profile, despite having had neither antiphospholipid antibodies nor any previous thrombotic event. A global appraisal of hemostasis should, if possible, be incorporated into clinical practice to detect the risk of a thrombotic event in patients with SLE and to consequently act to prevent its occurrence.

“Global” assays of hemostasis in modern obstetrical practice

It is known that during pregnancy, the hemostatic system, like the rest of the body's systems, undergoes certain changes: there is a gradual increase in the activity of coagulation unit of the hemostasis reaching a maximum before childbirth. However, if pregnancy is complicated by various hypertensive conditions, such as preeclampsia, an imbalance is observed in the hemostasis: against the background of an increase in the activity of coagulation link, depletion of anticoagulation factors and dysfunction of fibrinolytic system are observed. All these changes create a pathogenetic basis for the occurrence of severe thrombohemorrhagic complications that are fatal for both mother and fetus. Thus, the timely detection of these violations is an important task for modern obstetrics. Unfortunately, the applied screening methods for assessing the hemostasis system in practice provide extremely limited information: the tests have low sensitivity to hypercoagulation, as well as moderate to hypocoagulation, they do not allow to fully evaluate the dynamics of coagulation process in real time. In addition, when performing the same tests with reagents of different companies in the same patient, there may be a significant difference in the results. Disadvantages of screening tests became the reason for the search for a test to assess the functioning of the hemostatic system, which can reflect the complete picture of the state of blood coagulation system, and not of its individual links. Such tests are the so-called global tests for assessing the hemostatic system: thrombin generation test, thromboelastography, low-frequency piezothromboelastography and thrombodynamics. Each of the listed global tests has been successfully tested in obstetric and gynecological practice.

Haemostasis and minimally invasive extracorporeal circulation

<p>Advances in extracorporeal circulation using a minimally invasive circuit have rapidly emerged, and the components and biocoatings of the minimally invasive extracorporeal circuit (MiECC) have improved. The application range of minimally invasive cardiopulmonary bypass has expanded, however the main indications for the use of MiECCs during cardiac surgery have not yet been systematized. To the best of our knowledge, no guidelines for anticoagulant therapy regimens during minimally invasive cardiopulmonary bypass exist, and its effect on blood loss and the activation of coagulation in the perioperative period remain unclear. The present review highlighted the components of the circuit and the practical aspects of using MiECC. We formulated indications for the use of minimally invasive circuits and classified biocompatible coatings used to reduce the contact activation of haemostasis. According to the literature, when performing cardiopulmonary bypass with MiECC, the physiological haemostatic balance is disturbed. The detected changes in plasma haemostasis do not allow drawing conclusions regarding the advantages of MiECC, despite its clinical benefits. Multicentre randomized trials that comply with the rules of the pre-analytical stage of haemostasis and use global tests (thrombin generation test, thrombodynamics test, etc.) are required. The available studies on the haemostatic system using MiECC are not adequate for determining whether MiECCs on a haemostatic system are recommendable. However, MiECCs allow physicians to get closer to the fast track cardiac surgery ideal.</p><p>Received 7 October 2019. Revised 14 November 2019. Accepted 18 November 2019.</p><p><strong>Funding:</strong> The study did not have sponsorship.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p>

Test-takers’ perspectives on a global test of English: questions of fairness, justice and validity

Although language test-takers have been the focus of much theoretical and empirical work in recent years, this work has been mainly concerned with their attitudes to test preparation and test-taking strategies, giving insufficient attention to their views on broader socio-political and ethical issues. This article examines test-takers’ perceptions and evaluations of the fairness, justice and validity of global tests of English, with a particular focus upon the International English Language Testing System (IELTS). Based on relevant literature and theorizing into such tests, and on self-reported test experience data gathered from test-takers (N = 430) from 49 countries, we demonstrate how test-takers experienced fairness and justice in complex ways that problematized the purported technical excellence and validity of IELTS. Even as there was some evidence of support for the test as a fair measure of students’ English capacity, the extent to which it actually reflected their language capabilities was open to question. At the same time, the participants expressed concerns about whether IELTS was a vehicle for raising revenue and for justifying immigration policies, thus raising questions about the justness of the test. The research foregrounds the importance of focusing attention upon the socio-political and ethical circumstances that currently attend large-scale, standardized English language testing.

An omnibus test for the global null hypothesis

Global hypothesis tests are a useful tool in the context of clinical trials, genetic studies, or meta-analyses, when researchers are not interested in testing individual hypotheses, but in testing whether none of the hypotheses is false. There are several possibilities how to test the global null hypothesis when the individual null hypotheses are independent. If it is assumed that many of the individual null hypotheses are false, combination tests have been recommended to maximize power. If, however, it is assumed that only one or a few null hypotheses are false, global tests based on individual test statistics are more powerful (e.g. Bonferroni or Simes test). However, usually there is no a priori knowledge on the number of false individual null hypotheses. We therefore propose an omnibus test based on cumulative sums of the transformed p-values. We show that this test yields an impressive overall performance. The proposed method is implemented in an R-package called omnibus.

Mechanistic Basis for the Differential Effects of Rivaroxaban and Apixaban on Global Tests of Coagulation

Rivaroxaban and apixaban are both small molecules that reversibly inhibit factor Xa. Compared with rivaroxaban, apixaban has minimal effects on the prothrombin time and activated partial thromboplastin time. To investigate this phenomenon, we used a factor Xa-directed substrate in a buffer system. Although rivaroxaban and apixaban inhibited factor Xa with similar Ki values at equilibrium, kinetic measurements revealed that rivaroxaban inhibited factor Xa up to 4-fold faster than apixaban (p < 0.001). Using a discontinuous chromogenic assay to monitor thrombin production by prothrombinase in a purified system, rivaroxaban was 4-fold more potent than apixaban (Ki values of 0.7 ± 0.3 and 2.9 ± 0.5 nM, respectively; p = 0.02). Likewise, in thrombin generation assays in plasma, rivaroxaban prolonged the lag time and suppressed endogenous thrombin potential to a greater extent than apixaban. To characterize how the two inhibitors differ in recognizing factor Xa, inhibition of prothrombinase was monitored in real-time using a fluorescent probe for thrombin. The data were fit using a mixed-inhibition model and the individual association and dissociation rate constants were determined. The association rates for the binding of rivaroxaban to either free factor Xa or factor Xa incorporated into the prothrombinase complex were 10- and 1,193-fold faster than those for apixaban, respectively, whereas dissociation rates were about 3-fold faster. Collectively, these findings suggest that rivaroxaban and apixaban differ in their capacity to inhibit factor Xa and provide a plausible explanation for the observation that rivaroxaban has a greater effect on global tests of coagulation than apixaban.