Investigating the Multifaceted Nature of Radiation-Induced Coagulopathies in a Göttingen Minipig Model of Hematopoietic Acute Radiation Syndrome.

Coagulopathies are well documented after acute radiation exposure at hematopoietic doses, and radiation-induced bleeding is notably one of the two main causes of mortality in the hematopoietic acute radiation syndrome. Despite this, understanding of the mechanisms by which radiation alters hemostasis and induces bleeding is still lacking. Here, male Göttingen minipigs received hematopoietic doses of 60Co gamma irradiation (total body) and coagulopathies were characterized by assessing bleeding, blood cytopenia, fibrin deposition, changes in hemostatic properties, coagulant/anticoagulant enzyme levels, and markers of inflammation, endothelial dysfunction, and barrier integrity to understand if a relationship exists between bleeding, hemostatic defects, bone marrow aplasia, inflammation, endothelial dysfunction and loss of barrier integrity. Acute radiation exposure induced coagulopathies in the Göttingen minipig model of hematopoietic acute radiation syndrome; instances of bleeding were not dependent upon thrombocytopenia. Neutropenia, alterations in hemostatic parameters and damage to the glycocalyx occurred in all animals irrespective of occurrence of bleeding. Radiation-induced bleeding was concurrent with simultaneous thrombocytopenia, anemia, neutropenia, inflammation, increased heart rate, decreased nitric oxide bioavailability and endothelial dysfunction; bleeding was not observed with the sole occurrence of a single aforementioned parameter in the absence of the others. Alteration of barrier function or clotting proteins was not observed in all cases of bleeding. Additionally, fibrin deposition was observed in the heart and lungs of decedent animals but no evidence of DIC was noted, suggesting a unique pathophysiology of radiation-induced coagulopathies. These findings suggest radiation-induced coagulopathies are the result of simultaneous damage to several key organs and biological functions, including the immune system, the inflammatory response, the bone marrow and the cardiovasculature.

A Clot Twist: Extreme Variation in Coagulotoxicity Mechanisms in Mexican Neotropical Rattlesnake Venoms.

Rattlesnakes are a diverse clade of pit vipers (snake family Viperidae, subfamily Crotalinae) that consists of numerous medically significant species. We used validated in vitro assays measuring venom-induced clotting time and strength of any clots formed in human plasma and fibrinogen to assess the coagulotoxic activity of the four medically relevant Mexican rattlesnake species Crotalus culminatus, C. mictlantecuhtli, C. molossus, and C. tzabcan. We report the first evidence of true procoagulant activity by Neotropical rattlesnake venom in Crotalus culminatus. This species presented a strong ontogenetic coagulotoxicity dichotomy: neonates were strongly procoagulant via Factor X activation, whereas adults were pseudo-procoagulant in that they converted fibrinogen into weak, unstable fibrin clots that rapidly broke down, thereby likely contributing to net anticoagulation through fibrinogen depletion. The other species did not activate clotting factors or display an ontogenetic dichotomy, but depleted fibrinogen levels by cleaving fibrinogen either in a destructive (non-clotting) manner or via a pseudo-procoagulant mechanism. We also assessed the neutralization of these venoms by available antivenom and enzyme-inhibitors to provide knowledge for the design of evidence-based treatment strategies for envenomated patients. One of the most frequently used Mexican antivenoms (Bioclon Antivipmyn®) failed to neutralize the potent procoagulant toxic action of neonate C. culminatus venom, highlighting limitations in snakebite treatment for this species. However, the metalloprotease inhibitor Prinomastat substantially thwarted the procoagulant venom activity, while 2,3-dimercapto-1-propanesulfonic acid (DMPS) was much less effective. These results confirm that venom-induced Factor X activation (a procoagulant action) is driven by metalloproteases, while also suggesting Prinomastat as a more promising potential adjunct treatment than DMPS for this species (with the caveat that in vivo studies are necessary to confirm this potential clinical use). Conversely, the serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) inhibited the direct fibrinogen cleaving actions of C. mictlantecuhtli venom, thereby revealing that the pseudo-procoagulant action is driven by kallikrein-type serine proteases. Thus, this differential ontogenetic variation in coagulotoxicity patterns poses intriguing questions. Our results underscore the need for further research into Mexican rattlesnake venom activity, and also highlights potential limitations of current antivenom treatments.

Pharmacological management of rare coagulation factor deficiencies besides hemophilia.

INTRODUCTION: Rare coagulation factor deficiencies are less-known disorders with variable effects on the patient's life. Management of such patients is a challenge due to the paucity of evidence-based data, more so when patients with these rare disorders encounter a more rare, related condition, like inhibitor development or thrombosis. AREA COVERED: A comprehensive literature search related to RCFDs and management was performed in PubMed in order to discuss therapeutic options and challenges, prophylaxis, management of minor and major surgeries, obstetric and gynecological complications, inhibitor development, and thrombosis. EXPERT OPINION: Although significant changes have occurred in the management of RCFDs in recent years, more evidence-based studies besides expert opinion are needed for optimal management.

Thromboelastography Reaction-Time Thresholds for Optimal Prediction of Coagulation Factor Deficiency in Trauma.

BACKGROUND: Coagulopathy is common in multitrauma patients and repletion of procoagulant factor deficiency with fresh frozen plasma (FFP) improves hemostasis. Optimal kaolin-thromboelastography thresholds for FFP transfusion in trauma patients have not been well established. STUDY DESIGN: Adult trauma patients with an Injury Severity Score ≥15 were included in this retrospective observational cohort study. The primary end point was area under the receiver operating characteristic curve (AUROC) for reaction time (R-time) to detect procoagulant factor deficiency, as reflected by an elevated international normalized ratio (INR) or aPTT. Test characteristics for the optimal R-time threshold calculated in our study were compared against thresholds recommended by the American College of Surgeons for FFP transfusion. RESULTS: Six hundred and ninety-four pairs of thromboelastography and conventional coagulation tests were performed in 550 patients, with 144 patients having additional pairs of tests after the first hour. The R-time was able to detect procoagulant factor deficiency (INR ≥1.5 AUROC 0.80; 95% CI, 0.75 to 0.85; aPTT ≥40 seconds AUROC 0.85; 95% 0.80 to 0.89) and severe procoagulant factor deficiency (INR ≥2.0 AUROC 0.82; 95% CI, 0.73 to 0.99; aPTT ≥60 seconds AUROC 0.89; 95% CI, 0.81 to 0.98) with good accuracy. Optimal thresholds to maximize sensitivity and specificity were 3.9 minutes for detection of INR ≥1.5, 4.1 minutes for detection of aPTT ≥40 seconds, 4.3 minutes for detection of INR ≥2.0, and 4.3 for detection of aPTT ≥60 seconds. Currently recommended R-time thresholds for FFP transfusion had 100% specificity for detecting procoagulant factor deficiency, but low sensitivity (3% to 7%). CONCLUSIONS: R-time can detect procoagulant factor deficiency in multitrauma patients with good accuracy, but currently recommended R-time thresholds are highly specific and not sensitive. Use of low-sensitivity thresholds might result in undertreatment of many patients with procoagulant factor deficiency.

Oral contraceptive use increases risk of inflammatory and coagulatory disorders in women with Polycystic Ovarian Syndrome: An observational study.

Polycystic ovarian syndrome (PCOS) is a multispectral disorder requiring lifelong management. Its pathophysiology is still being explored which makes its treatment options restrained. Present study explores impact of oral contraceptive mode of treatment on metabolic, hormonal, inflammation and coagulation profile of PCOS women. 50 subjects diagnosed with Rotterdam criteria receiving no drug treatment served as controls whereas 50 subjects receiving only OCPs (Ethinyl estradiol 0.03 mg, Levonorgestrel 0.15 mg) as a mode of treatment at least for six-months served as cases. Ferriman-Gallwey score and hormonal profile improved on OCP treatment. However, parameters like weight, Body mass index, waist-hip ratio, Oral glucose tolerance test, lipid profile, insulin, HOMA-IR, adiponectin, interleukin1ß, visfatin, resistin, tissue factor, PT and APTT showed considerable derangements in OCP group. All above parameters are associated with the risk of diabetes mellitus, dyslipidemia, coronary vascular disease, cancers, hypercoagulable state, venous thromboembolism and thrombotic events. Long-term use of OCPs needs to be considered carefully for PCOS patients who are already burdened with associated risk factors. This study was conducted in a region where women do not have much access to high-end screening and diagnostic facilities that further exacerbates their clinical outcomes. Large scale, long-term studies need to be designed to further evaluate safety use of OCPs in PCOS women.

Rare clotting factor deficiency among Sudanese children.

: Rare clotting factor (F) deficiency is a deficiency of one or more of coagulation factors other than FVIII, FIX and vonWillebrand (FI, FII, FV, FV + FVIII, FVII, FIX, FX, FXI and FXIII) that cause bleeding disorders and are inherited as autosomal recessive. Descriptive study was conducted in Hemophilia Centre, Khartoum, Sudan. The medical files of pediatric patients presented to the center were reviewed retrospectively. Forty-seven patients (male : female ratio = 1.2 : 1) were included. The majority (93.6%) have parental history of consanguinity and around one third (31.9%) have family history of bleeding disorder. FV deficiency was the most common deficient factor (36.2%) followed by FI deficiency (23.4%) and FX111 deficiency (21.3%). Bruising (46.8%) and epistaxis (25.5%) were the most common presenting complains. FV deficiency mainly presented with cutaneous ecchymosis (47.1%). FI deficiency presented with umbilical bleeding (45.5%) and FXIII presented with cutaneous ecchymosis (50%). Rare clotting factor deficiency is an existing disease in Sudan with the male : female ratio was 1.2 : 1. FV deficiency, FI deficiency, FXIII deficiency were the common deficiency encountered.

Plasma contact factors as therapeutic targets.

Direct oral anticoagulants (DOACs) are small molecule inhibitors of the coagulation proteases thrombin and factor Xa that demonstrate comparable efficacy to warfarin for several common indications, while causing less serious bleeding. However, because their targets are required for the normal host-response to bleeding (hemostasis), DOACs are associated with therapy-induced bleeding that limits their use in certain patient populations and clinical situations. The plasma contact factors (factor XII, factor XI, and prekallikrein) initiate blood coagulation in the activated partial thromboplastin time assay. While serving limited roles in hemostasis, pre-clinical and epidemiologic data indicate that these proteins contribute to pathologic coagulation. It is anticipated that drugs targeting the contact factors will reduce risk of thrombosis with minimal impact on hemostasis. Here, we discuss the biochemistry of contact activation, the contributions of contact factors in thrombosis, and novel antithrombotic agents targeting contact factors that are undergoing pre-clinical and early clinical testing.

Acute fatty liver of pregnancy: clinical outcomes and expected duration of recovery.

OBJECTIVE: Our aim was to provide a description of clinical and laboratory finding: pregnancy outcomes in women with acute fatty liver of pregnancy (AFLP). We also characterize the duration of recovery of multiorgan system dysfunction that begins after delivery. STUDY DESIGN: All women who were admitted to Parkland Hospital with AFLP were identified; their clinical and laboratory findings, pregnancy outcomes, and postpartum resolution of AFLP were reviewed. RESULTS: Between 1975 and 2012, there were 51 women who were identified to have AFLP. The most common complaints were persistent nausea and vomiting (57%), hypertension (57%), and abdominal pain (53%). More than 90% of these women had at least 1 of these findings or combinations thereof. A combination of hepatic and renal dysfunction was nearly universal, but with variable severity. Procoagulant synthesis was impaired in more than three-fourths of the women, which served to intensify obstetric hemorrhage for which 50% of the 51 women received blood and component transfusions. The stillbirth rate was 120 of 1000 pregnancies, and there were 2 maternal deaths. Composite recovery times of various markers of hepatic and renal function indicated normalization of most laboratory values within 7-10 days after delivery. CONCLUSION: The clinical features and laboratory findings of women with AFLP derive from the central pathologic process: liver failure. After delivery, clinical recovery typically is seen within 3-4 days; however, laboratory abnormalities can persist for much longer.

Preoperative plasma hyperfibrinogenemia is predictive of poor prognosis in patients with nonmetastatic colon cancer.

BACKGROUND: The outcomes of colorectal cancer are determined by host factors, including systemic inflammation. The purpose of this study was to evaluate the prognostic significance of fibrinogen and inflammation-based scores, as markers of the inflammatory response, in colon cancer. METHODS: We retrospectively reviewed the medical records of patients with nonmetastatic colon cancer who underwent curative resection between January 2005 and December 2007. Fibrinogen, albumin, C-reactive protein, neutrophil, lymphocyte, and platelet counts were measured at the time of diagnosis. Correlations between preoperative plasma fibrinogen levels and clinicopathologic characteristics were analyzed. Univariate and multivariate survival analyses were performed to identify factors associated with disease-free and overall survival. RESULTS: A total of 624 patients who underwent curative resection for colon cancer were eligible for this study. Mean preoperative plasma fibrinogen levels were 325.24±88.19 mg/dl. Higher preoperative plasma fibrinogen levels were associated with sex (male), old age, poorly/mucinous differentiated tumor, advanced tumor stage, elevated carcinoembryonic antigen (CEA) levels, higher modified Glasgow Prognostic Score, and higher neutrophil:lymphocyte and platelet:lymphocyte ratios. In multivariate analysis, elevated plasma fibrinogen level [disease-free survival: hazard ratio (HR) 1.999, 95% confidence interval (95% CI) 1.081-3.695, P=.027; overall survival: HR 3.138, 95% CI 1.077-9.139, P=.036], advanced tumor stage, and higher CEA levels were independently associated with worse disease-free survival and overall survival. None of the inflammation-based scores were significantly associated with survival. CONCLUSIONS: Fibrinogen as one of inflammatory markers may be considered a possible prognostic marker in colon cancer.

PML/RARalpha fusion protein transactivates the tissue factor promoter through a GAGC-containing element without direct DNA association.

A severe coagulopathy is a life-threatening complication of acute promyelocytic leukemia (APL) and is ascribable mainly to the excessive levels of tissue factor (TF) in APL cells regulated in response to the promyelocytic leukemia/retinoic acid receptor alpha (PML/RARalpha) fusion protein. The underlying molecular mechanisms for this regulation remain ill-defined. With U937-PR9 cell lines stably expressing luciferase reporter gene under the control of different mutants of the TF promoter, both luciferase and ChIP data allowed the localization of the PML/RARalpha-responsive sequence in a previously undefined region of the TF promoter at position -230 to -242 devoid of known mammalian transcription factor binding sites. Within this sequence a GAGC motif (-235 to -238) was shown to be crucial because deletion or mutation of these nucleotides impaired both PML/RARalpha interaction and promoter transactivation. However, EMSA results showed that PML/RARalpha did not bind to DNA probes encompassing the -230 to -242 sequences, precluding a direct DNA association. Mutational experiments further suggest that the activator protein 1 (AP-1) sites of the TF promoter are dispensable for PML/RARalpha regulation. This study shows that PML/RARalpha transactivates the TF promoter through an indirect interaction with an element composed of a GAGC motif and the flanking nucleotides, independent of AP-1 binding.

Elective fresh frozen plasma in the critically ill: what is the evidence?

The scientific rationale for administering fresh frozen plasma (FFP) rests on the assumptions that patients are at risk of adverse effects from inadequate coagulation factors, and that FFP transfusions can decrease those risks. There is a general but unfounded enthusiasm for FFP use across a range of clinical specialties in hospital practice. Plasma for transfusion is most often used when a patient has abnormal results on coagulation screening tests, either as therapy in the face of bleeding, or in patients who are not bleeding as prophylaxis before invasive procedures or surgery. Laboratory abnormalities of coagulation are considered by many clinicians to help predict bleeding before invasive procedures where bleeding risk exists; FFP is presumed to improve the laboratory results and reduce this risk. However, most guideline indications for the prophylactic use of FFP are not supported by evidence from good-quality randomised trials. In fact, the strongest randomised controlled trial evidence indicates that prophylactic plasma for transfusion is not effective across a range of clinical settings. This is supported by data from non-randomised studies in patients with mild-moderate abnormalities in coagulation tests. It is also crucial to clearly understand the risks associated with use of FFP, as no studies have taken adequate account of the extent to which adverse effects might negate the clinical benefits of treatment with FFP. New trials are needed to evaluate the efficacy and adverse effects of plasma, both in bleeding and non-bleeding patients, and to determine whether presumed benefits outweigh the real risks. In addition, new haemostatic tests that better define the risk of bleeding and monitor the effectiveness of FFP use should be validated.

Predicting abnormal coagulation in ischemic stroke: reducing delay in rt-PA use.

Normal prothrombin time (PT) and partial thromboplastin time (PTT) are recommended for administration of recombinant tissue-plasminogen activator (rt-PA) in stroke, but waiting for results can delay use. We examined the charts of 365 stroke patients to assess predetermined risk factors associated with elevated PT/PTT. Elevated PT/PTT can be predicted in patients taking warfarin or heparin/heparinoid or on hemodialysis, according to emergency department triage, with 100% sensitivity and 94.7% specificity. These results could be applied to rt-PA candidates and reduce potential delays.

Amyloidosis and bleeding: pathophysiology, diagnosis, and therapy.

Amyloid diseases can be associated with potentially life-threatening hemorrhage. Pathogenetic factors contributing to the abnormal bleeding tendency in this setting are heterogeneous and depend on the type of amyloidosis and pattern of organ involvement. In patients with light-chain (AL) amyloidosis, acquired hemostatic abnormalities, including coagulation factor deficiencies, hyperfibrinolysis, and platelet dysfunction, can be regarded as the most important pathogenetic factors. In patients with other types of amyloidosis, acquired hemostatic defects are rare, and amyloid deposition has also been reported to be the main cause of abnormal bleeding manifestations. Amyloid angiopathy with increased fragility of blood vessels and impaired vasoconstriction may promote bleeding in this setting. Rupture of solid organs caused by amyloid deposition also was reported. Whereas therapeutic options in bleeding caused by local amyloid deposition are restricted to supportive measures and, in severe cases, surgery, acquired hemostatic defects may be treated according to the causative mechanism. In this review, we focus on bleeding risks in patients with amyloid diseases. Current concepts with regard to pathophysiology, diagnosis, and treatment are summarized and discussed.

Functional characterization of fibrinogen Bicêtre II: a gamma 308 Asn-->Lys mutation located near the fibrin D:D interaction sites.

The effects of the gamma-308 Asn-->Lys substitution of fibrinogen Bicêtre II on clot formation, structure and properties were determined to elucidate the role of this part of the molecule in fibrin polymerization. This process was followed by measurement of turbidity, and the structure and biophysical characteristics of the clots were studied by permeation, scanning electron microscopy, and rheological techniques. Turbidity studies revealed an increased lag period and greater final turbidity for fibrin BII clots, indicating impaired oligomer formation. By permeation it was found that BII clots had greater network porosity, four times more than that of the control. The clot architecture visualized by scanning electron microscopy was similar to that of control clots with pore size and fiber diameter slightly increased. BII clots had a stiffness decreased by more than half, and an increased loss tangent, a measure of the inelastic deformation of the clot. All these results suggest a disruption of the proper alignment of fibrin monomers during oligomer formation. Consistent with these results, fibrin cross-linking by adding the physiological concentration of factor XIII to the purified protein showed that gamma and alpha chain cross-linking was impaired in BII clots. This amino acid substitution defines distinctive effects on the surface of the D:D interaction sites that are reflected in the clot structure and functional properties.

Acquired von Willebrand syndrome: an underdiagnosed and misdiagnosed bleeding complication in patients with lymphoproliferative and myeloproliferative disorders.

Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder with laboratory findings similar to those for congenital von Willebrand disease (VWD). Unlike the congenital disease, AVWS usually occurs in individuals with no personal or family history of bleeding. The prevalence of AVWS in the general population is unknown because data from large prospective studies of this syndrome are not available. Although AVWS is particularly frequent in lymphoproliferative or myeloproliferative disorders, it can also be associated with solid tumors, immunologic and cardiovascular disorders, and other miscellaneous conditions. Diagnosis of AVWS is based on assays measuring the activity of von Willebrand factor (VWF). This tends to be abnormally low, but factor VIII (FVIII) coagulant activity can sometimes be normal. FVIII/VWF inhibiting activity is found in only a minority of cases. Bleeding episodes in patients with AVWS are mostly of the mucocutaneous type and can be managed with desmopressin, plasma-derived FVIII/VWF concentrates, and intravenous immunoglobulin (IVIg). Recombinant activated factor VII can be useful in patients unresponsive to standard therapy. An updated version of the International Registry on AVWS, recently available online, will provide more information on this rare, but underdiagnosed and misdiagnosed, disorder.

Neonatal coagulation problems.

Bleeding problems often occur during the neonatal period. Although thrombocytopenia is the most common cause, coagulation problems often occur, and the two problems may co-exist. The causes, diagnosis, and management of coagulation problems in newborn infants are reviewed.

Antidotes to haemorrhage: recombinant factor VIIa.

Recombinant Factor VIIa (rFVIIa) concentrates were originally developed to treat the refractory bleeding complications associated with allo-antibody inhibitors in hemophilias A and B. As experience was gained in the hemophilias, the physiology of rFVIIa and its successes in controlling bleeds stimulated rFVIIa use in other challenging medical conditions complicated by bleeding. Thus, rFVIIa has assumed the role of a 'universal pancoagulant' without sufficient evidence-based data from well-designed, adequately powered clinical trials. This chapter discusses the anecdotal experience with rFVIIa based upon the few controlled trials that do exist, and emphasizes that these empirical dosing strategies have not yielded the best approach to achieve effective control of bleeding. Evidence-based data are necessary to establish the cost-benefit and risk-benefit profiles of rFVIIa, and to establish it as a standard treatment for bleeding.