Tyrosine-O-sulfation is a widespread affinity enhancer among thrombin interactors

Tyrosine-O-sulfation is a common post-translational modification (PTM) of proteins following the cellular secretory pathway. First described in human fibrinogen, tyrosine-O-sulfation has long been associated with the modulation of protein–protein interactions in several physiological processes. A number of relevant interactions for hemostasis are largely dictated by this PTM, many of which involving the serine proteinase thrombin (FIIa), a central player in the blood-clotting cascade. Tyrosine sulfation is not limited to endogenous FIIa ligands and has also been found in hirudin, a well-known and potent thrombin inhibitor from the medicinal leech, Hirudo medicinalis. The discovery of hirudin led to successful clinical application of analogs of leech-inspired molecules, but also unveiled several other natural thrombin-directed anticoagulant molecules, many of which undergo tyrosine-O-sulfation. The presence of this PTM has been shown to enhance the anticoagulant properties of these peptides from a range of blood-feeding organisms, including ticks, mosquitos and flies. Interestingly, some of these molecules display mechanisms of action that mimic those of thrombin's bona fide substrates.

Advances in the management of haemophilia: emerging treatments and their mechanisms

Mainstay haemophilia treatment, namely intravenous factor replacement, poses several clinical challenges including frequent injections due to the short half-life of recombinant factors, intravenous administration (which is particularly challenging in those with difficult venous access), and the risk of inhibitor development. These impact negatively upon quality of life and treatment compliance, highlighting the need for improved therapies. Several novel pharmacological therapies developed for haemophilia aim to rebalance the clotting cascade and potentially circumvent the aforementioned challenges. These therapies utilise a range of different mechanisms, namely: the extension of the circulating half-life of standard recombinant factors; the mimicking of factor VIII cofactor activity; rebalancing of coagulation through targeting of natural anticoagulants such as antithrombin and tissue factor pathway inhibitor; and inducing the production of endogenous factors with gene therapy. These therapies carry the potential of revolutionising haemophilia treatment by alleviating the current challenges presented by mainstay factor replacement. This review will provide an overview of the key trial findings related to novel therapies based on the mechanisms described above.

41 Low Flow Priapism as A Complication of Covid-19 Infection

On 12 March 2020 the World Health Organisation (WHO) declared a pandemic of SARS-COV-2(Covid 19). We report a case of a 58-year-old man who presented with dyspnoea, pyrexia and a dry cough. Upon admission he was noted to be in a severe Type 1 Respiratory Failure with Bi-lateral pulmonary infiltrates suggestive of Covid 19 infection. Rapid transfer to ITU ensued with Intubation, Ventilation and Inotropic support. Priapism was noted a day into admission which was subsequently aspirated by the Urology team, achieving detumescence. Priapism is a state of persistent penile erection that continues for 4 hours beyond sexual stimulation. We describe the role of thrombosis, dysregulation of the clotting cascade and acute disseminated intravascular coagulation (DIC) as shared pathologies in priapism and Covid 19 infection. We highlight the importance of vigilance for extra-pulmonary manifestations of Covid-19 and feel that the pro-thrombotic phenomena exhibited by Covid-19 infection affects distal vasculature in the same manner as Low Flow Priapism and hence explains why our patient suffered from this particular urological complication

Resusitasi Pengendalian Kerusakan Di Unit Perawatan Intensif

Abstrak Resusitasi dengan pengendalian kerusakanmenggambarkan suatu pendekatan ke perawatan awal pada pasien dengan cedera berat. Tujuan pendekatan ini untuk menjaga pasien tetap stabil dengan menghindari intervensi dan kondisi yang berisiko kepada keadaan perburukan dengan mengendalikan trias kematian, yaitu hipotermia, koagulopati, dan asidosis. Merupakan hal yang penting bahwa konsep dan kepraktisan pendekatan ini dipahami oleh semua yang terlibat dalam manajemen awal pasien trauma. Pendekatan ini dimulai dengan pemberian produk darah sejak awal, penghentian perdarahan dan pengembalian volume darah yang bertujuan untuk mengembalikan stabilitas fisiologis dengan cepat. Resusitasi dengan pengendalian kerusakan memilikibeberapa tambahan pendekatan dari bidang farmakologis dan laboratorium untuk meningkatkan perawatan pasien yang mengalami perdarahan. Pendekatan ini termasuk trombelastografi sebagai ukuran rinci kaskade pembekuan, asam traneksamat sebagai antifibrinolitik. Kata kunci : hipotermia, koagulopati, asidosis, perdarahan masif Damage Control Resuscitation in Intensive Care Unit Abstract Damage control resuscitation (DCR) describes an approach to the early care of very seriously injured patients. The aim is to keep the patient alive whilst avoiding interventions and situations that risk worsening their situation by driving the lethal triad of hypothermia, coagulopathy and acidosis.It is critical that the concepts and practicalities of this approach are understood by all those involved in the early management of trauma patients. Damage control resuscitation forms part of an overall approach to patient care rather than a specific intervention and has evolved from damage control surgery. It is characterised by early blood product administration, haemorrhage arrest and restoration of blood volume aiming to rapidly restore physiologic stability. The infusion of large volumes of crystalloid is no longer appropriate, instead the aim is to replace lost blood and avoid dilution and coagulopathy. In specific situations, permissive hypotension may also be of benefit, particularly in patients with severe haemorrhage from an arterial source. Damage control resuscitation has been augmented by both pharmacologic and laboratory adjuncts to improve the care of the hemorrhaging patient. These include thrombelastography as a detailed measure of the clotting cascade, tranexamic acid as an antifibrinolytic. Keywords: hypothermia, coagulopathy, acidosis, massive bleeding

­­­­­­­A type I IFN, prothrombotic hyperinflammatory neutrophil signature is distinct for COVID-19 ARDS­­­

Background: Acute respiratory distress syndrome (ARDS) is a severe critical condition with a high mortality that is currently in focus given that it is associated with mortality caused by coronavirus disease 2019 (COVID-19). Neutrophils play a key role in the lung injury characteristic of non-COVID-19 ARDS and there is also accumulating evidence of neutrophil mediated lung injury in patients who succumb to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: We undertook a functional proteomic and metabolomic survey of circulating neutrophil populations, comparing patients with COVID-19 ARDS and non-COVID-19 ARDS to understand the molecular basis of neutrophil dysregulation. Results: Expansion of the circulating neutrophil compartment and the presence of activated low and normal density mature and immature neutrophil populations occurs in ARDS, irrespective of cause. Release of neutrophil granule proteins, neutrophil activation of the clotting cascade and upregulation of the Mac-1 platelet binding complex with formation of neutrophil platelet aggregates is exaggerated in COVID-19 ARDS. Importantly, activation of components of the neutrophil type I interferon responses is seen in ARDS following infection with SARS-CoV-2, with associated rewiring of neutrophil metabolism, and the upregulation of antigen processing and presentation. Whilst dexamethasone treatment constricts the immature low density neutrophil population, it does not impact upon prothrombotic hyperinflammatory neutrophil signatures. Conclusions: Given the crucial role of neutrophils in ARDS and the evidence of a disordered myeloid response observed in COVID-19 patients, this work maps the molecular basis for neutrophil reprogramming in the distinct clinical entities of COVID-19 and non-COVID-19 ARDS.

Coagulation factors directly cleave SARS-CoV-2 spike and enhance viral entry

Coagulopathy is recognized as a significant aspect of morbidity in COVID-19 patients. The clotting cascade is propagated by a series of proteases, including factor Xa and thrombin. Other host proteases, including TMPRSS2, are recognized to be important for cleavage activation of SARS-CoV-2 spike to promote viral entry. Using biochemical and cell-based assays, we demonstrate that factor Xa and thrombin can also directly cleave SARS-CoV-2 spike, enhancing viral entry. A drug-repurposing screen identified a subset of protease inhibitors that promiscuously inhibited spike cleavage by both transmembrane serine proteases as well as coagulation factors. The mechanism of the protease inhibitors nafamostat and camostat extend beyond inhibition of TMPRSS2 to coagulation-induced spike cleavage. Anticoagulation is critical in the management of COVID-19, and early intervention could provide collateral benefit by suppressing SARS-CoV-2 viral entry. We propose a model of positive feedback whereby infection-induced hypercoagulation exacerbates SARS-CoV-2 infectivity.

Biologic Hemostatic Agents in Obstetrics and Gynecology

In Obstetrics and Gynecology, the practice of biologic hemostatic agents in the field are generally used to augment the basic tenets of hemostasis to decrease the morbidity and mortality of such procedures. These hemostatic agents work along with the body’s physiology to rapidly aid in platelet plug formation, activation of the clotting cascade, the creation of fibrin, and to form a stable clot. The four main sub-categories of hemostatic agents include mechanical, biological, flowable, and fibrin sealants. Mechanical agents act as scaffolding for platelet aggregation to form a platelet plug. Biological agents activate clotting factors in the coagulation cascade to aid in hemostasis. Flowable agents combine biologic with mechanical agents to stabilize clot formation while also providing mechanical tamponade. Fibrin sealants combine high levels of fibrin and thrombin that when combined, form a fibrin clot at an accelerated speed. Hemostatic agents in obstetrics are often used in the setting of postpartum hemorrhage, cesarean delivery and postpartum hysterectomy to decrease the rate of morbidity most commonly seen with abnormal placentation and uterine atony. With gynecologic surgery, hemostatic agents are more commonly used then in obstetrics. They aid in hemostasis with common gynecologic procedures including hysterectomies, ovarian cystectomies, myomectomies, endometriosis cases, incontinence procedures and malignant debulking procedures. Also, with the increase in minimally invasive surgical techniques, topical hemostasis can aid in fewer transfusions, improved visualization in the surgical field decreased operative time and reduction in the risk of conversion to laparotomy.

­­­­­­­A type I IFN, prothrombotic hyperinflammatory neutrophil signature is distinct for COVID-19 ARDS­­­

Background: Acute respiratory distress syndrome (ARDS) is a severe critical condition with a high mortality that is currently in focus given that it is associated with mortality caused by coronavirus disease 2019 (COVID-19). Neutrophils play a key role in the lung injury characteristic of non-COVID-19 ARDS and there is also accumulating evidence of neutrophil mediated lung injury in patients who succumb to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: We undertook a functional proteomic and metabolomic survey of circulating neutrophil populations, comparing patients with COVID-19 ARDS and non-COVID-19 ARDS to understand the molecular basis of neutrophil dysregulation. Results: Expansion of the circulating neutrophil compartment and the presence of activated low and normal density mature and immature neutrophil populations occurs in ARDS, irrespective of cause. Release of neutrophil granule proteins, neutrophil activation of the clotting cascade and upregulation of the Mac-1 platelet binding complex with formation of neutrophil platelet aggregates is exaggerated in COVID-19 ARDS. Importantly, activation of components of the neutrophil type I interferon responses is seen in ARDS following infection with SARS-CoV-2, with associated rewiring of neutrophil metabolism, and the upregulation of antigen processing and presentation. Whilst dexamethasone treatment constricts the immature low density neutrophil population, it does not impact upon prothrombotic hyperinflammatory neutrophil signatures. Conclusions: Given the crucial role of neutrophils in ARDS and the evidence of a disordered myeloid response observed in COVID-19 patients, this work maps the molecular basis for neutrophil reprogramming in the distinct clinical entities of COVID-19 and non-COVID-19 ARDS.

Folding DNA to foil the clotting cascade

Origami-inspired DNA aptamer arrays prevent blood clotting in hemodialysis circuits.

Terminal Phase Components of the Clotting Cascade in Patients with End-Stage Renal Disease Undergoing Hemodiafiltration or Hemodialysis Treatment

Hemostasis disorder in patients with end-stage renal disease (ESRD) is frequently associated with bleeding diathesis but it may also manifest in thrombotic complications. Analysis of individual coagulation and fibrinolytic factors may shed light on the background of this paradox situation. Here we explored components essential for fibrin formation/stabilization in ESRD patients being on maintenance hemodiafiltration (HDF) or hemodialysis (HD). Pre-dialysis fibrinogen, factor XIII (FXIII) antigen concentrations and FXIII activity were elevated, while α2-plasmin inhibitor (α2PI) activity decreased. The inflammatory status, as characterized by C-reactive protein (CRP) was a key determinant of fibrinogen concentration, but not of FXIII and α2PI levels. During a 4-h course of HDF or HD, fibrinogen concentration and FXIII levels gradually elevated. When compensated for the change in plasma water, i.e., normalized for plasma albumin concentration, only FXIII elevation remained significant. There was no difference between HDF and HD treatments. Individual HDF treatment did not influence α2PI activity, however after normalization it decreased significantly. HD treatment had a different effect, α2PI activities became elevated but the elevation disappeared after normalization. Elevated fibrinogen and FXIII levels in ESRD patients might contribute to the increased thrombosis risk, while decreased α2PI activity might be associated with elevated fibrinolytic potential.