bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasminogen Activator Inhibitor (PAI-1) and Non-insulin-dependent Diabetes in Pima Indians, South Asians and Europeans
Authors: Nagi D K , Knowler W C , Hanson R L , Mohamed Ali V , Yudkin J S 
Published: July 2018

SummaryActivity of plasminogen activator inhibitor-1 (PAI-1), a potent inhibitor of fibrinolysis, is raised in non-insulin-dependent diabetes mellitus (NIDDM) and may contribute to excess macrovascular disease. We investigated the association of PAI-1 activity with NIDDM in Pima Indians, a racial group with low risk of coronary artery disease, but in whom the impact of NIDDM on the occurrence of coronary artery disease is similar to other racial groups. We studied 308 (136 nondiabetic, 172 diabetic) Pima Indians from Arizona, and 138 (98 nondiabetic, 40 diabetic) South Asians and 129 (80 non-diabetic, 49 diabetic) Europeans living in North London. PAI-1 activity was measured by a spectrophotometric assay, and insulin, intact proinsulin and des 31,32 proinsulin concentrations were measured employing highly specific monoclonal antibody-based assays. Compared with non-diabetic subjects, PAI-1 activity was significantly higher in subjects with NIDDM among South Asians (22.8 ± 7.3 vs. 17.4 ± 6.9 AU/ml, p <0.001) and Europeans (23.1 ± 6.6 vs. 16.5 ± 6.1 AU/ml, p <0.001) but not among Pima Indians (19.5 ± 9.6 vs. 18.5 ± 8.6 AU/ml, ns). The association of PAI-1 activity with diabetes remained statistically significant when controlled for age, sex, body mass index and waist-hip ratio, serum triglyceride and fasting insulin concentrations in South Asians (p <0.001) and Europeans (p <0.001). The relationships of PAI-1 activity with clinical and biochemical variables were similar in the three racial groups other than for fasting and 2 h plasma glucose concentrations which were significantly associated with PAI-1 activity in South Asians (partial r = 0.32 and 0.31) and Europeans (partial r = 0.44 and 0.50) but not in Pima Indians (partial r = 0.11 and 0.15). In Pima Indians with NIDDM, PAI-1 activity was similar in those treated with sulphonylureas, insulin, or no drugs for diabetes. In conclusion, the association of PAI-1 with diabetes differs in racial groups who are at different risk of NIDDM and ischaemic heart disease. Previously reported differences in the prevalence of ischaemic heart disease between diabetic and non-diabetic Pima Indians, and between non-diabetic subjects from the three racial groups, are unlikely to be due to differences in PAI-1 activity.
Functional Consequences of Mutations in Amino Acid Residues that Stabilize Calcium Binding to the First Epidermal Growth Factor Homology Domain of Human Protein C
Authors: Geng Jie-Ping , Cheng Chong-Hui , Castellino Francis J 
Published: July 2018

SummaryCharge-to-alanine mutations of three amino acid residues, viz., D46, D48, and D/Hya71, which are known to be important in stabilizing Ca2+ binding to epidermal growth factor (EGF) domains of vitamin K-de-pendent blood coagulation proteins, have been engineered into recombinant human protein C (r-PC), The resulting variants were then employed to assess the importance of this Ca2+ binding site in the activation properties of r-PC and in the activity of activated protein C (APC). Another mutation, of D48 to E, was constructed in order that a more conservative mutation at the Ca2+ binding site could be similarly examined.The mutant proteins were fully processed with regard to proper signal peptide cleavage, γ-carboxylation, and β-hydroxylation, except, of course, for the D71A mutant in this latter case. The D48E variant possessed an additional residue of γ-carboxyglutamic acid (Gla), showing that E48 was γ-carboxylated. All of the mutants were reactive against a monoclonal antibody (MAb) specific for a Ca2+-dependent epitope within the amino-terminus of the Gla domain of r-PC, demonstrating that a proper Ca2+-dependent conformation was adopted in this region of the protein. None of the mutants, except for [D48γ]r-PC, were reactive against another Ca2+-dependent MAb which possessed specificity for Ca2+ binding to the EGF1 region of PC-this being the area of the protein that contained the mutated residues. These data strongly suggest that the alanine mutations present at D46, D48, and D71 diminished Ca2+ binding to the EGF1 domain of r-PC.Steady state kinetic analysis demonstrated that determinants for the Ca2+-dependent inhibition of the thrombin (flla)-catalyzed activation of r-PC, and for the kinetic recognition of the flla/thrombomodulin complex, were not dependent on the integrity of the Ca2+ sites present in EGF1. The lone exception was [D48γ]r-PC, which did not undergo inhibition by Ca2+, an effect likely due to the potential for altered coordination of Ca2+ due to the Gla insertion, rather than to a dependency on D48. Plasma-based anticoagulant assays, as well as individual factor Va and factor Villa inactivation assays, showed that only [D71A]r-APC possessed a significantly reduced activity compared to wild-type r-APC. These observations suggest that D/Hya71 is likely an important determinant for activity of APC toward its physiological substrates, factor Va and factor Villa.
Immunologic Assessment of Patients Treated with Bovine Fibrin as a Hemostatic Agent
Authors: Carroll John F , Moskowitz Keith A , Edwards Niloo M , Hickey Thomas J , Rose Eric A , Budzynski Andrei Z 
Published: July 2018

SummaryTwenty-one cardiothoracic surgical patients have been treated with fibrin as a topical hemostatic/sealing agent, prepared from bovine fibrinogen clotted with bovine thrombin. Serum samples have been collected before treatment with fibrin and postoperatively between 1 and 9 days, 3 and 12 weeks, and 6 and 8 months. The titers of anti-bovine fibrinogen antibodies, measured by ELISA specific for immunoglobulins IgG or IgM, increased to maximal values after about 8 or 6 weeks, respectively. After 8 months, IgG titers were on average 20-fold lower than the mean maximal value, while IgM titers returned to the normal range. IgG was the predominant anti-bovine fibrinogen immunoglobulin as documented by ELISA, affinity chromatography and electrophoresis. Anti-bovine fibrinogen antibodies present in patients reacted readily with bovine fibrinogen, but did not cross-react with human fibrinogen as measured by ELISA or by immunoelectrophoresis. A significant amount of antibodies against bovine thrombin and factor V has been found, many cross-reacting with the human counterparts. No hemorrhagic or thrombotic complications, or clinically significant allergic reactions, occurred in any patient, in spite of antibody presence against some bovine and human coagulation factors. The treatment of patients with bovine fibrin, without induction of immunologic response against human fibrinogen, appeared to be an effective topical hemostatic/sealing measure.
European Concerted Action on Anticoagulation (ECAA) - The Multicentre Calibration of Rabbit and Human ECAA Reference Thromboplastins
Authors: Poller L , Barrowcliffe T W , van den Besselaar A M H P , Jespersen J , Tripodi A , Houghton D ,   Prepared on behalf of the ECAA by the above steering committee
Published: July 2018

SummaryTwo candidate ECAA reference preparations have been calibrated in a multicentre exercise at 14 representative national laboratories to provide reference thromboplastin for a large field study in 16 European countries. Two preparations were required because of the established differences in ISI arising from the two main routes of calibration via rabbit and human IRP. To be comparable with working reagents in everyday use a human plain recombinant reagent of low ISI and a rabbit plain preparation of moderately high ISI were selected. A precise calibration of the two candidate preparations has been achieved with the manual PT technique and an ISI of 0.95 (SE 0.0078) for the human reagent and 1.67 (SE 0.0322) for the rabbit reagent.
Isolated Familial Plasminogen Deficiency May not Be a Risk Factor for Thrombosis
Authors: Tait R C , Walker Isobel D , Conkie J A , Islam S I A M , McCall Frances 
Published: July 2018

SummaryDespite many reports of individuals with congenital plasminogen deficiency and thrombosis, there is still uncertainty whether heterozygous deficiency represents a real thrombophilic risk factor or simply a coincidental finding. We have addressed this issue by testing for plasminogen deficiency in a cohort of 9611 blood donors. Out of 66 donors with reduced plasminogen activity on two occasions 28 were shown to have a familial deficiency state (including 3 with dysplasminogen-aemia). Our observed prevalence rate for familial plasminogen deficiency, calculated at 2.9/1000 (95% Cl = 1.9-4.2 per 1000), was not significantly different from that calculated from published reports of congenital plasminogen deficiency in thrombotic cohorts (5.4/1000). Furthermore, with only two exceptions, all 80 donors and relatives with familial deficiency were asymptomatic with regard to thrombosis -including a 29 year old donor with suspected compound heterozygous hypoplasminogenaemia. These findings add further weight to the argument that familial heterozygous plasminogen deficiency, at least in isolation, does not constitute a significant thrombotic risk factor. However, it remains uncertain whether plasminogen deficiency, when combined with other thrombophilic conditions, may become more clinically important.
Soluble P-selectin as Parameter for Platelet Activation during Storage
Authors: Kostelijk E H , Fijnheer R , Nieuwenhuis H K , Gouwerok C W N , de Korte D 
Published: July 2018

SummaryPlatelet concentrates stored at room temperature deteriorate. The so-called storage lesion is characterised by morphological changes and a loss of functionality. To find an assay for early platelet activation in platelet concentrates the morphological score, β-TG release and P-selectin expression were determined, and compared with the amount of soluble P-selectin. An ELISA was used to quantify soluble P-selectin in the storage medium. We found a significant correlation between the amount of soluble P-selectin and the percentage of P-selectin positive platelets (flow-cytometric analysis) (r = 0.7449; p <0.0001) or the amount of β-TG release (r = 0.6837; p<0.0001). The morphological score also correlated significantly (negative) with the amount of soluble P-selectin (r = -0.7669; p = 0.0002). From day 0 till day 8, the amount of soluble P-selectin increased constantly from 219 ± 49.2ng/ml to 556 ± 102.3 ng/ml. The detection of soluble P-selectin can be used to quantify activation of platelets during storage. The immuno-assay for soluble P-selectin is more sensitive than flow-cytometric analysis of the percentage of P-selectin-positive cells and allows earlier detection of platelet activation.
Ongoing Prothrombotic State in the Portal Circulation of Cirrhotic Patients
Authors: Violi Francesco , Ferro Domenico , Basili Stefania , Lionetti Raffaella , Rossi Elisabetta , Merli Manuela , Riggio Oliviero , Bezzi Mario , Capocaccia Livio 
Published: July 2018

SummaryPortal thrombosis may complicate the clinical course of cirrhosis, but the pathophysiologic mechanism is unclear. Aim of the study was to evaluate the behavior of clotting system and endotoxemia in portal vein and in peripheral circulation of 11 cirrhotic patients undergoing transjugular port-systemic shunt (TIPS).Portal blood showed higher values of Fl+2 [Median (range): 2.5 (1.1-5.3) vs. 1.1 (0.6-2.1) nM, p <0.01], D-dimer [765 (184-1713) vs. 192 (64-813) ng/ml, p < 0.01] and endotoxemia [31 (16-47.2) vs. 13.7 (7.5-23.5) pg/ml, p <0.01] than peripheral circulation. In the portal vein, all but one sample had Fl+2 > 1.2 nM (upper limit of control values), all but one had D-dimer > 216 mg/dl (mean + 2 SD of controls) and 100% had values of endotoxemia > 9.6 pg/ml (upper limit of control values). Fibrinogen was lower in the portal circulation compared to peripheral circulation but the difference was not significant [85 (58-195) vs. 134 (75-244) mg/dl, p > 0.05].Endotoxemia was directly correlated with Fl+2 (Rho = 0.92 p <0.006) and D-dimer (Rho = 0.93, p <0.005).This study shows that an ongoing prothrombotic state is present in the portal circulation of cirrhotic patients and may play a pivotal role in the thrombotic episodes occurring in this clinical setting.
Enhancement of Plasminogen Binding to U937 Cells and Fibrin by Complestatin
Authors: Tachikawa Kiyoshi , Hasurni Keiji , Endo Akira 
Published: July 2018

SummaryPlasminogen binds to endothelial and blood cells as well as to fibrin, where the zymogen is efficiently activated and protected from inhibition by α2-antiplasmin. In the present study we have found that complestatin, a peptide-like metabolite of a streptomyces, enhances binding of plasminogen to cells and fibrin. Complestatin, at concentrations ranging from 1 to 5 μM, doubled 125I-plasminogen binding to U937 cells both in the absence and presence of lipoprotein(a), a putative physiological competitor of plasminogen. The binding of 125I-plasminogen in the presence of complestatin was abolished by e-aminocaproic acid, suggesting that the lysine binding site(s) of the plasminogen molecule are involved in the binding. Equilibrium binding analyses indicated that complestatin increased the maximum binding of 125I-plasminogen to U937 cells without affecting the binding affinity. Complestatin was also effective in increasing 125I-plasminogen binding to fibrin, causing 2-fold elevation of the binding at ~1 μM. Along with the potentiation of plasminogen binding, complestatin enhanced plasmin formation, and thereby increased fibrinolysis. These results would provide a biochemical basis for a pharmacological stimulation of endogenous fibrinolysis through a promotion of plasminogen binding to cells and fibrin.
The Ability of Thrombin Inhibitors to Reduce the Thrombin Activity Generated in Plasma on Extrinsic and Intrinsic Activation
Authors: Prasa D , Svendsen L , Stürzebecher J 
Published: July 2018

SummaryIn a thrombin generation test with continuous registration of thrombin activity in plasma we studied the ability of a variety of thrombin inhibitors of different type and mechanism of action to influence the activity of thrombin after activation of the coagulation system. Depending on the inhibitor, the peak of thrombin activity is delayed and/or reduced.By blocking the active site of generated thrombin inhibitors cause a concentration dependent reduction of the thrombin peak and inhibit feed-back reactions of thrombin resulting in a delay of thrombin generation. Highly potent synthetic active-site directed inhibitors (Ki ≤ 20 nM) reduce the thrombin activity formed in plasma after extrinsic or intrinsic activation with the same efficiency (IC50 0.1 - 0.6 μM) as hirudin. The delay and reduction of thrombin generation by inhibitors of the anion-binding exosite 1 of thrombin is only attributed to an inhibition of feed-back reactions of thrombin. For a 50% reduction of thrombin activity in plasma by this type of inhibitors relatively high concentrations were determined.
Thrombi Formed in a Chandler Loop Mimic Human Arterial Thrombi in Structure and PAI-1 Content and Distribution
Authors: Robbie Linda A , Young Simon P , Bennett Bruce , Booth Nuala A 
Published: July 2018

SummaryWe have previously shown that whole blood clots prepared under static conditions are a poor model for human thrombi formed in vivo. The most striking contrast is in the PAI-1 content, some 100 times lower in static clots than in human thrombi. This study aimed to evaluate thrombi formed in an artificial circulation (Chandler loop) using whole blood augmented with platelets. Citrated blood was recalcified and placed in tubing, which was sealed to form a closed loop and circulated. Immunohistochemical staining revealed morphology very similar to human thrombi formed in vivo, comprising dense platelet-rich heads and fibrin-rich tails. Strong positive staining for PAI-1 was observed in fibrin-rich areas of both the head and the tail. The PAI-1 content of the thrombi increased significantly on augmentation of blood with isolated platelets, and reached levels comparable with those in human thrombi. These Chandler thrombi thus provide an appropriate model system for the study of thrombus lysis, in contrast to static blood clots.
Surface-Secreted von Willebrand Factor Mediates Aggregation of ADP-Activated Platelets at Moderate Shear Stress: Facilitated by GPIb but Controlled by GPIIb-IIIa
Authors: Frojmovic M M , Kasirer-Friede A , Goldsmith H L , Brown E A 
Published: July 2018

SummaryWe previously showed that ADP activation of washed human platelets in plasma-free suspensions supports aggregation at moderate shear stress (0.4-1.6 Nm-2) in Poiseuille flow. Although most activated platelets expressed maximal fibrinogen-occupied GPIIb-IIIa receptors, aggregation appeared to be independent of bound fibrinogen, but blocked by the hexapeptide GRGDSP. Here, we tested the hypothesis that von Willebrand factor (vWF) secreted and expressed on activated platelets mediates aggregation at moderate shear rates from 300 to 1000 s_1 corresponding to shear stresses from 0.3 to 1.1 Nm-2. Relatively unactivated platelets (<15% expressing prebound fibrinogen) were prepared from acidified citrated platelet rich plasma (cPRP) by single centrifugation with 50 nM stable prostacyclin derivative ZK 36374 and resuspended in Tyrodes-albumin at 5 X 104 cells ε_1. Flow cytometric measurements with monoclonal antibody (mAb) 2.2.9 reporting on surface-bound vWF, and with mAb S12 reporting on a-granule secreted P-selectin, showed that 65% and 80%, respectively, of all platelets were maximally activated with respect to maximal secretion and surface expression of these proteins. “Resting” washed platelets exhibited both surface-bound vWF and significant P-selectin secretion. We showed that mAbs 6D1 and NMC4, respectively blocking the adhesive domains on the GPIb receptor recognizing vWF, and on the vWF molecule recognizing the GPIb receptor, partially inhibited ADP-induced aggregation under shear in Couette flow, the degree of inhibition increasing with increasing shear stress. In contrast, mAb 10E5, blocking the vWF binding domain on GPIIb-IIIa, essentially blocked all aggregation at the shear rates tested. We conclude that vWF, expressed on ADP-activated platelets, is at least the predominant cross-bridging molecule mediating aggregation at moderate shear stress. There is an absolute requirement for free activated GPIIb-IIIa receptors, postulated to interact with platelet-secreted, surface bound vWF. The GPIb-vWF cross-bridging reaction plays a facilitative role becoming increasingly important with increasing shear stress. Since aurin tricarboxylic acid, which blocks the GPIb binding domain on vWF, was also found to completely block aggregation in Poiseuille flow, we conclude that it too affects the GPIIb-IIIa interaction.
Long-term Follow-up of Hemostatic Molecular Markers during Remission Induction Therapy with All-Trans Retinoic Acid for Acute Promyelocytic Leukemia
Authors: Watanabe Reiko , Murata Mitsuru , Takayama Nobuyuki , Tokuhira Michihide , Kizaki Masahiro , Okamoto Shinichiro , Kawai Yohko , Watanabe Kiyoaki , Murakami Hiroshi , Kikuchi Masao , Nakamura Shin , Ikeda Yasuo ,   For Keio Hematology-Oncology Cooperative Study Group (KHOCS)
Published: July 2018

SummaryHemostatic molecular markers were serially monitored in a prospective fashion during remission induction therapy with all-trans retinoic acid (ATRA) in sixteen patients with acute promyelocytic leukemia (APL). One patient with leukocytosis before treatment and three patients who later developed hyperleukocytosis also received chemotherapy with behenoyl Ara-C and daunorubicin. Plasma levels of E-fragment of fibrin and fibrinogen degradation product (FDP-E), FDP-D dimer (D-D), thrombin-antithrombin complex (TAT), and plasmin-α2 plasmin inhibitor complex (PIC) were markedly elevated in all but one patient before treatment, and these parameters decreased to normal or near normal ranges in most patients within the first 7 days of treatment. Interestingly, we have found that these parameters were again elevated during the later course of ATRA therapy (after day +7) in eleven patients for various reasons including cytotoxic chemotherapy (3 cases), fever (5 cases; 2 cases with apparent infection, 3 cases without known etiology), Caesarean section (1 case), and no apparent etiology (2 cases). Three patients showed bleeding complications during reelevation of molecular markers, but none developed thrombosis. Plasma elastase-α1 proteinase inhibitor complex (E-α1PI) was markedly elevated in all patients at diagnosis and did not decrease significantly during ATRA therapy. Plasma tissue factor antigen was mildly elevated in one out of four patients studied, and thrombomodulin was elevated in two out of ten patients tested. These results confirmed the rapid normalization of coagulopathy during the early phase of remission induction therapy with ATRA but suggest that re-elevation of molecular markers occurs frequently during the later course of ATRA therapy.
Gender Differences in Platelet GPIIb-IIIa Activation
Authors: Faraday Nauder , Goldschmidt-Clermont Pascal J , Bray Paul F 
Published: July 2018

SummaryGender differences in the development of thrombotic diseases have been described in numerous clinical settings. Enhanced platelet reactivity in both sexes is associated with the development of vascular thromboses. Because activation of platelet GPIIb-IIIa receptors is a central event in thrombus formation, we examined GPIIb-IIIa function in normal male and female volunteers. Using flow cytometry, we quantitated gender differences in the number of binding sites for FITC-labeled fibrinogen (FITC-FGN) and FITC-labeled PAC-1 antibody (FITC-PAC-1). Washed platelets were incubated with either FITC-FGN or FITC-PAC-1 and activated with either ADP or thrombin receptor activating peptide (TRAP) prior to cytometric acquisition of data. The dissociation constant for FITC-FGN was the same in both sexes (approx. 1.6 x 10-7M), however, the number of GPIIb-IIIa receptors per platelet capable of binding fibrinogen was significantly greater in women than men in response to 20μM ADP (16,319 ± 1871 vs 9669±1994, p = 0.02), 20μM ADP (39,951 ± 4711 vs 25,948 ± 4953, p = 0.05) and 50μM TRAP (39,236 ± 3965 vs 21,848 ± 4159, p = 0.007). Similarly, the number of GPIIb-IIIa receptors capable of binding PAC-1 in response to ADP and TRAP was 50% to 80% greater in women than men. Binding experiments using specific anti-GPIIb-IIIa monoclonal antibodies (P2 and 10E5), as well as quantitative Western blotting experiments, showed no gender difference in the total number of GPIIb-IIIa molecules expressed. Analysis of data from female subgroups demonstrated an association of GPIIb-IIIa reactivity with menstrual phase. We conclude that GPIIb-IIIa receptors on platelets from premenopausal women are more “activatable” than those on platelets from young men. Variations in the serum concentrations of estrogens and/or progestins may modulate GPIIb-IIIa function.