bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compound Heterozygosity for a Novel Mutation Combined with G Insertion in Exon 13 Causes Severe Factor XI Deficiency in Patients of Japanese Origin.
Authors: Ishikawa Nobutsune , Yasunaga Shinichiro , Ohtsubo Motoaki , Takihara Yoshihiro , Sato Takashi , Kobayashi Masao 
Published: April 2020

Abstract
Factor XI (FXI) deficiency is a rare autosomal recessive coagulopathy. However, it is one of the most common inherited disorders among Ashkenazi Jews. FXI deficiency is characterized by undetectable levels of FXI antigen and coagulant activity. Patients with FXI deficiency usually suffered from mild to moderate bleeding manifestations. Up to now, more than 80 gene mutations responsible for FXI deficiency have been reported including three common mutations (Type I, II and III) in Ashkenazi Jews. However, it has been reported that significantly higher frequency of allelic heterogeneity has been observed in different ethnic groups. We have studied the molecular basis of this disease in a Japanese family. Two children with FXI deficiency who are siblings have frequent epistaxis. Blood coagulation tests showed severely prolonged aPTT with normal PT. FXI coagulant activities of both patients were less than 1% activity. Their father and mother had normal aPTT, but the activities of FXI in parents showed 45% and 52% activities, respectively. Prolonged aPTT restored to normal range by the addition of recombinant Factor VIIa (NovoSevenR) dose-dependently, indicating the possible efficacy for the replacement therapy in this disorder. FXI gene mutations were screened by a PCR. We identified a novel mutation, C to G transversion in exon 12 in the FXI gene. The C to G transversion in exon 12 results in a missense mutaion (Q433E). That leads to the disruption of catalytic domain structure of FXI molecule. Another mutation was found in G insertion in exon 13, which was previously reported in only one Japanese patient, causes the frameshift, resulting in substitution of last 105 amino acids (Tyr503-Val607) with 32 abnormal amino acid residues. This change also induces the destruction of the catalytic domain of FXI. Thus, the compound heterozygous novel mutations found in Japanese are not identical to those in Ashkenazi Jews, suggesting that this mutation may not be of the same ancestry.
The Metalloprotease ADAMTS13 Is a Natural Anti-Thrombotic.
Authors: Chauhan Anil K. , Motto David G. , Lamb Colin B. , Dockal Michael , Scheiflinger Friedrich , Ginsburg David , Wagner Denisa D. 
Published: April 2020

Abstract
The metalloprotease ADAMTS13 cleaves highly adhesive ultra large von Willebrand factor (UL-VWF) multimers after their release from the endothelium. UL-VWF is stored in Weibel-Palade bodies of endothelial cells. ADAMTS13 deficiency is linked to a life threatening disorder, thrombotic thrombocytopenic purpura (TTP), which is characterized by VWF and platelet-rich thrombi in the microvasculature, and may lead to organ ischemia, neurological dysfunction and ultimately death. We previously confirmed in vivo that in Adamts13−/− mice and not in wild-type mice “strings of platelets” formed after endothelial activation. The VWF strings remain attached at one end to the endothelium and “waved” the other end in the blood stream. In addition, we showed prolonged adhesion of platelets to secreted VWF on endothelium of Adamts13−/− mice. The possible role of ADAMTS13 in platelet plug formation has not been addressed previously. We investigated thrombosis in venules and arterioles of Adamts13−/− mice by intravital microscopy. Mesenteric microvenules were stimulated with calcium ionophore A23187, a secretagouge of Weibel-Palade bodies. In the Adamts13−/− mice we observed spontaneous thrombus formation in the activated microvenules. Inhibitory antibody to plasma ADAMTS13 induced thrombi formation in the activated microvenules and prolonged adhesion of platelets to secreted VWF on endothelium of wild-type mice. In the ferric chloride arterial injury model we found that the number of fluorescent platelets deposited within 2–3 min on the sub-endothelium after injury was unexpectedly higher in Adamts13−/− mice as compared to Adamts13+/+ mice (P&lt;0.05). In the Adamts13−/− mice, platelet plug grew faster as thrombi &gt;30 um were seen at 6.6±0.9 min compared to 10.8±0.8 min in the Adamts13+/+ mice (P&lt;0.005). The platelet plug reached occlusive size in 10.6±0.7 min in Adamts13−/− mice, whereas in the Adamts13+/+ mice all the vessels were still open at this time. In the Adamts13+/+, the mean vessel occlusion time was 16.7±1.2 min after injury (P&lt;0.0005). Thus ADAMTS13, by cleaving VWF multimers, down regulates both platelet adhesion to exposed subendothelium and thrombus growth. Furthermore, we observed that recombinant human ADAMTS13 inhibited formation of VWF platelet strings in histamine-activated venules and promoted thrombi dissolution in the Adamts13−/− mice. Our findings reveal that ADAMTS13 has natural anti-thrombotic activity and recombinant ADAMTS13 could be used as an anti-thrombotic agent.
Successful Bilateral Cataract and Circumcision Operation Performed in a Hemophilia-A Patient with Inhibitors by Using Recombinant Factor VIIa.
Authors: Kilinc Yurdanur , Sasmaz Ilgen , Leblebistan Goksel , Antmen Bulent , Sizmaz Selcuk , Yagmur Meltem , Cayli Sibel 
Published: April 2020

Abstract
Objective: Prothrombin complex concentrates (PCC), active prothrombin complex concentrates (APCC;FEIBA) or recombinant Factor VIIa (rFVIIa; Novoseven) are safely used for the treatment of hemorrhages in hemophiliac patients with inhibitors or during the interventions performed in these patients. A hemophilia-A patient with inhibitors in whom bilateral cataract operation and circumcision were successfully performed by rFVIIa administration was presented.
Case: The 13 year old male patient had been diagnosed with severe Hemophilia-A by the detection of a FVIII level below 1% in the factor assay performed due to echhymoses in his body when he was 6 months old. The inhibitor level of the patient who developed bilateral cataract during the follow-up period was determined as 2.95 BU; however the cataract operation had to be delayed due to the absence of an adequate increase in his factor VIII level despite the 2000 U factor replacement administered in July 2002. The patient was readmitted to the hospital for operation in October 2002. However, the operation was delayed again since a safe level of factor VIII wasn’t achieved with Factor VIII replacement. The patient was excluded from follow-up for approximately 2 years. In August 2004, the patient was hospitalized due to echhymosis in the scrotum, and his factor VIII level was measured as 1% and the VIII inhibitor level as 88 BU. IV steroid treatment was initiated in the patient at a dose of 2 mg/kg, with the factor VIII replacement intended at a level of 100 U/kg. 2 doses of 90 microgram/kg of rFVIIa were administered at a two-hour interval due to catheterization for plasmapheresis and subsequently, plasmapheresis program was carried out. The inhibitor level was measured as 25.6 BU after the first plasmapheresis. Factor VIII level of the patient whose FVIII inhibitor level declined to 15.4 BU with these treatments, didn’t exceed 3%. 120 microgram/kg rFVIIa was administered to the patient prior to operation and maintained during the 1st and 2nd days of the operation every 2–3 hours at the same dose. At this operation, right eye small incision cataract extraction and posterior chamber intraocular lens implantation were performed under general anesthesia. A month later, cataract operation was performed in the other eye together with the circumcision operation. A 3-grade increase was achieved in visual acuity of both eyes.
Conclusion: Here, the cataract operation together with the circumcision operation performed in a hemophiliac patient with inhibitors was presented, demonstrating that rFVIIa which has been started to be used also in other fields other than hemophilia patients, can be used safely in operations.
FranceCoag Network: A National Multicenter Prospective Cohort for Congenital Bleeding Disorders.
Authors: Fressinaud Edith , Dieval Jocelyne , Gay Valerie , Guerin Viviane , Lambert Thierry , Donadieu Jean , FranceCoag Reseau 
Published: April 2020

Abstract
The FranceCoag Network is a prospective national cohort of patients affected with hemophilia and severe hereditary hemorrhagic diseases except platelet disorders. It has been set up in France since January 2003 as replacement of a previous project only dedicated to hemophilia. The objectives are to know the exhaustive number, type and characteristics of these patients registered in hemophilia centers. Inclusion criteria are: FVIII or IX defect (&lt;30%), severe defect (&lt;10%) in FII, V, VII, X, XI, XIII or FI (&lt; 0.1 g/l) or severe VWD. Once per year centers send datas on severe bleeding episodes, surgery, replacement therapy i.e. type of concentrate, units, place of treatment and main complications (including new inhibitors). These data are collected and monitored by a coordinating center attached to a public health institution (InVS). Direct transmission of datas via a highly protected web site is foreseen for the end of 2005. The follow-up of the study is ensured by a steering committee (regional coordinators, clinicians, committed health institutions, representatives of patients association) periodically extended to scientific experts and other public health agencies. Beside its epidemiologic interest, this cohort will also promote research projects on this population such as Pups cohort (defined as severe hemophilia A or B patients with none or few cumulative exposure days at the enrolment). On July 2005, 3469 patients were included by 37 centers. The diagnosis are hemophilia A n=2594 (75%); hemophilia B n=539 (15%), VWD n=239 (7%), severe defect in other coagulation factor: n= 97 (3%). At their inclusion, 373 patients (11%) were infected by HIV1, 1383 (40%) had a positive HCV serology, while 365 patients (10%) were co infected by HIV1 and HCV. Among this cohort, 45 deaths were observed since 1994, which represent 4.5 deaths per 1 000 years-patients (95% CI: [3.3–6.0]). Deaths were related to AIDS or HCV in 19 cases. Inhibitors was observed in 388 patients (11%) (hemophilia A: n=369, hemophilia B n=15, VWD n=2, FXIII defect n= 1, FV defect n=1). The incidence of inhibitor during the follow-up was 9.4 cases per 1000 person-years.
Potential Role of ADAMTS13/FXI Complexes in the Pathogenesis of End Stage Renal Disease.
Authors: Fareed Jawed , Hoppensteadt D. , Cunanan J. , Patel C. , Maddineni J. , Baltasar F. , Fareed D. , Demir M. , Tobu M. , Iqbal O. , Bansal V. , Greenfield R. 
Published: April 2020

Abstract
ADAMTS13 alternatively known as von Willebrand Factor (vWF) cleaving protease is a Zinc metalloprotease which cleaves macromolecular M-vWF multimers at the Tyr (1605)-Met (1606) bond located in the AT domain of vWF. Down regulation of ADAMTS13 is known to be associated with thrombotic thrombocytopenic purpura (TTP). ADAMTS13 forms stable complex with factor XI and factor XIa. Measurement of ADAMTS13/FXI complexes in plasma may provide additional information on the pathogenesis of ESRD associated thrombotic complications. ADAMTS13/FXI can be measured using an ELISA based immunoassay. A polyclonal antibody reacts with a peptide in C-terminal region of the ADAMTS13 molecule is quoted on the micro titer plate. ADAMTS13 present in these test samples bind the antibody. After washing the bound ADAMTS13/FXI complexes were quantified. To test the hypothesis that ADAMTS13 levels are altered in ESRD, blood samples from 62 patients with ESRD prior to dialysis session were collected. Control group comprised of 34 normal healthy age match controls. The vWF antigen levels were also measured in both the groups using an ELISA method. The ESRD group exhibited a marked variation in the ADAMTS13/FXI complex levels with a range of 0 to 1100% (mean = 161±315) of the 62 samples. Eleven patients exhibited a greater than 250% where as the 51 patients exhibited less than 100 % complex. The distribution of ADMTS13/FXI complex was bi-modal. In the normals, the ADAMTS13/FXI complex activity ranges from 147–201% with a mean of 169±16. Unlike the ESRD population the normal group exhibited guassian distribution. The vWF antigen levels relatively higher in the ESRD patients (175±30) vs the normal (88±19). These results suggest that ADAMTS13/FXI is dysregulated in ESRD patients. While most of the patients exhibit a marked decrease in ADAMTS13 level, some of these patients exhibit markedly higher levels. Such fluctuation in the ADAMTS13/FXI level may contribute to the potential thrombotic and bleeding complications in ESRD pathogenesis.
Evidence for Control of von Willebrand Factor Multimer Size by Intramolecular Thiol-Disulfide Exchange.
Authors: Ganderton Tim , Chesterman Colin N. , Berndt Michael C. , Hogg Philip 
Published: April 2020

Abstract
Plasma von Willebrand factor (VWF) is a multimeric glycoprotein from endothelial cells and platelets that mediates adhesion of platelets to sites of vascular injury. In the shear force of flowing blood, however, only the very large VWF multimers are effective in capturing platelets. The multimeric size of VWF is controlled by proteolysis at the Tyr842-Met843 peptide bond by ADAMTS13. It is apparent, however, that VWF multimers are processed to a significant degree in the absence of ADAMTS13 in mice and humans. This finding implies that another mechanism of controlling VWF multimer size must exist. We noticed similarities between the structural control of α-keratin and VWF. Both are multimeric elongated proteins whose substrates are linked by disulfide-bonds and both proteins undergo shear-dependent conformational change. Keratin shape is controlled by thiol-mediated events and we have shown that the free thiol of thrombospondin-1 can facilitate cleavage of the disulfide-bonds that hold VWF multimers together. The structure of α-keratin is controlled by shear-dependent intramolecular thiol-disulfide exchange. Free thiols in keratin from unpaired cysteines exchange with nearby disulfides when the α-keratin fibre is exposed to shear. The thiol-disulfide exchange process continues until the shear across the fibre is resolved. We hypothesized that a similar mechanism may be operating in VWF. Intramolecular thiol-disulfide exchange is dependent on the presence of at least one unpaired cysteine thiol in the protein. Using a biotin-linked maleimde that specifically alkylates free thiols, we have shown that plasma VWF does contain unpaired cysteine residues. VWF was coated onto the interior of glass capillary tubes and exposed to shear using a precision syringe pump. VWF eluted from the tube when shear was stepped, but not when the shear was constant, and the eluted VWF was of smaller multimer size than that bound to the tube. These observations imply that VWF multimer size can be controlled by intramolecular thiol-disulfide exchange. We suggest that this mechanism may be responsible for the processing of VWF multimer size observed in the absence of ADAMTS13.
Formation of Procoagulant Platelet Derived Microparticles through Platelet GPIb-Interaction with Von Willebrand Factor under High Shear Stress.
Authors: Reininger Armin J. , Heijnen Harry F.G. , Schumann Hannah , Schramm Wolfgang , Ruggeri Zaverio M. 
Published: April 2020

Abstract
We describe here novel findings of the mechanism of initial platelet contact with immobilized von Willebrand factor (VWF) under high shear stress and how this leads to the formation of procoagulant platelet derived microparticles. In a parallel plate perfusion chamber whole blood was perfused over multimeric VWF or dimeric VWF A1 domain at shear rates between 2,000 s−1 and 40,000 s−1. Platelet attachment to VWF always occurred through glycoprotein Ibα receptors located in discrete adhesion points (DAPs), i.e. few limited membrane areas of 0.05 to 0.1 μm2 that arrested the platelets on the surface. The ongoing flow translocated such anchored platelets downstream, thus pulling membrane tethers from the intact and unstimulated platelet. Tethers could remain connected with the platelet body or be eventually severed, which occurred preferentially at shear rates above 6,000 s−1. Depending on the length of the severed membrane fragment they represented either isolated tethers or microparticles (arrowheads; see Figure below), the latter defined by a diameter of 50 to 100 nanometers. The shear rate threshold for microparticle formation was between 6,000 s−1 and 10,000 s−1. Immuno-fluorescence and immuno-electron microscopy showed glycoprotein Ibα clustered in DAPs of microparticles and tethers, i.e. the contact sites with the surface immobilized VWF. The microparticles also exhibited tissue factors on their surface and showed significant procoagulant activity measured by thrombin generation. We propose that after GPIbα anchoring to VWF in flowing blood passive mechanical pulling of membrane from platelets may generate platelet derived microparticles that can potentially support thrombogenesis.
Figure Figure
Comparison of Activated Partial Thromboplastin Time Ratios with Ecarin Clotting Time Ratios for Monitoring Direct Thrombin Inhibitor Therapy: In-Vitro Study and Case Study of Lepirudin Therapy.
Authors: Messmore Harry L. , Fabbrini Nancy J. , Badrinath Ketty , Harriman Richard , Iqbal Omar , Bird Mary Lourdes 
Published: April 2020

Abstract
The direct thrombin inhibitors lepirudin and argatroban are widely used to treat heparin induced thrombocytopenia (HIT). It has been suggested that the Ecarin™ (Echis carinatus venom) clotting time may be superior to the activated partial thromboplastin time (APTT) for monioring purposes. We have prepared standard curves for lepirudin (Refludan™) and Argatroban covering therapeutic drug levels and corresponding APTT ratios (clotting time/control clotting time). Ecarin™ clotting time ratios were performed to demonstrate the practical application of these curves in the clinical care of patients. We report the case of an 80 year old man with HIT/HITT syndrome that occurred during therapy for deep vein thrombosis (DVT) with a low molecular weight heparin (LMWH). His initial coagulation studies were abnormal due to warfarin and LMWH therapy. The patient had a moderate impairment of renal function. Lepirudin therapy in a bolus dose of 14 mg (patient weight: 103.0 kg) resulted in supratherapeutic blood levels of drug and hematuria (Platelet count: 〉200 x 103). Dosage adjustment to maintain an APTT ratio of 1.5 for five days caused no hematuria, but thromboembolic complications occurred at that ratio. The in-vitro dose response curve for Lepirudin was compared with the Ecarin™ clotting time (ECT) ratio at those same concentration ranges in the same plasma. For comparison, Argatroban dose response curves in-vitro were made as well. ECT ratios were very similar to the APTT ratios in the patient’s samples. Representative ratios after the initial bolus, during the infusion period of five days and at the termination of that period are shown in the following table:
Comparison of APTT and ECT Ratios APTT Ratio ECT Ratio 1.43 1.07 3.98 3.08 2.91 1.95 2.74 1.95 2.79 1.90 2.58 1.78 2.44 2.42 3.83 4.78
Conclusion: The ECT ratios reflect a steeper dose response curve than that observed with the APTT ratios. This may permit more accurate measurement of blood levels using ECT ratios.
Two Cases of Pediatric Hit Requiring Unusually High Doses of Direct Thrombin Inhibitors: Does a Subset of Such Patients Exist?.
Authors: Grabowski Eric F. , Buonanno Ferdinando S. , Doody Daniel , Van Cott Elizabeth M. , Grant Patricia E. , Jones Robin M. , Whalen Michael , Nowiski Natan 
Published: April 2020

Abstract
Experience in pediatrics with heparin-induced thrombocytopenia (HIT) with or without thrombosis is currently limited. In the past two years, however, we have cared for two children with HIT who have required unusually high doses of direct thrombin inhibitors in order to maintain a PTT in the 50–80 sec range. Neither child had any recognizeable congenital or acquired risk factor(s) for hypercoagulability, including activated protein C resistance, prothrombin mutation G20210A, deficiency of protein C or S, anticardiolipin antibodies, or elevated levels of homocysteine or lipoprotein (a).
Case 1: A 6 year old girl presented with persistant headache, left-sided weakness, and right lateral gaze paresis. Head CT and MR showed saggital and transverse sinus thrombosis, as well as the presence of two intraparenchymal hemorrhages. Treatment in the first 24 hrs consisted of catheter-directed thromborhexis to recanalize the left transverse sinus and prevent the otherwise anticipated development of complete obstruction to drainage from the right cerebral cortex, followed by low-dose unfractionated heparin (10 U/kg/hr) to inactivate thrombus-bound thrombin released acutely by the thromborhexis. While full anticoagulation was sought by hr 48, this was achieved only over several days owing to a high heparin requirement (45 U/kg/hr) to obtain therapeutic heparin levels. Neurologic status improved over the next several days. However, on day 14 our patient suffered acute loss of vision, following by a drop in platelet count and identification of HIT antibody. She was placed on argatroban, but to attain a therapeutic PTT, required an inordinately high dose (15μg/kg/min, vs “usual” dose of 2). When she was switched to r-hirudin, an unusually high dose (0.7 mg/kg/hr, vs “usual” dose of 0.2) was again required.
Case 2: A 2-and-a-half year old girl was admitted for ECMO following development of respiratory failure due to necrotizing strep. pneumoniae. After 5 days on unfractionated heparin, her platelet count dropped, she developed skin necrosis, and HIT antibody was identified. She was placed on r-hirudin, but also required an unusually high dose (0.52 mg/kg/hr) to achieve a therapeutic PTT. We are aware of two other pediatric cases of such high requirements for direct thrombin inhibitors at other institutions, although a review of the literature makes clear that most instances of pediatric HIT are managed satisfactorily with doses/kg consistent with adult practice. We hypothesize that a subset of chidren with HIT require a significantly higher dose of direct thrombin inhibitors on the basis of a relatively enhanced ability to generate thrombin in the presence of HIT antibody. Studies of thrombin generation and inhibition in our two patients are in progress.