bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poor Comparability of Prothrombin Fragment 1 + 2 Values Measured by Two Commercial ELISA Methods: Influence of Different Anticoagulants and Standards
Authors: Tripodi Armando , Chantarangkul Veena , Bottasso Biancamaria , Mannucci Pier Mannuccio 
Published: July 2018

SummaryWe compared F 1 + 2 results obtained with two commercial ELISA methods (Behring and Baxter) assaying the same plasma samples. There was little correlation between the results of the two methods, as shown by the low correlation coefficient (r = 0.50) and by low percentage of concordant classification (normal or abnormal) of the samples (24%). Such poor correlation is probably due to the different anticoagulants suggested, because correlation improved when both methods were carried out in plasmas collected with the same anticoagulant. However, the Baxter method still gave significantly lower F 1 + 2 values than the Behring method. Assuming that this difference is due to the use of standards with different F 1 +2 concentrations, the standards from Behring and Baxter were evaluated by both methods. Parallel dose-response curves were obtained when the standards were run by the Behring method but not by the Baxter method, indicating that the two standards are qualitatively different. This study demonstrates that the two F 1 + 2 methods give different values for the same samples and that these values are poorly correlated. Standardization of the F 1 + 2 assays cannot be achieved easily simply by using a common standard and the use of different anticoagulants appears to be the main reason for poor standardization.
Serum Lipid Profile Determines Platelet Reactivity to Native and Modified LDL-Cholesterol in Humans
Authors: Katzman Per L , Bose Ratna , Henry Stephen , McLean Donna L , Walker Shaun , Fyfe Christopher , Perry Yvette , Mymin David , Bolli Peter 
Published: July 2018

SummaryThe effects of thrombin (0.2 U/ml) and native (n-LDL), malon- dialdehyde-modified (MDA-LDL) and auto-oxidized (ox-LDL) low-density lipoproteins (20 μg of protein/ml) on platelet activation were evaluated in seven hyperlipidemic patients and compared to seven controls (fasting serum cholesterol 8.49 ± 0.5 and 4.61 ± 0.4 mM, respectively). Basal and thrombin-induced increases in platelet intracellular free calcium ion concentration ([Ca2+; fura-2) were similar in hyperlipidemic patients and controls (45 ± 5 vs 42 ± 3 and 635 ±51 vs 599 ± 69 mM, respectively). n-LDL, MDA-LDL and ox-LDL increased basal [Ca2+]; (16, 36 and 81 percent, p <0.01 between LDL-types), increases were consistently smaller in patients. There was an inverse relationship between LDL-induced responses and fasting serum LDL cholesterol as well as LDL/HDL ratio.In conclusion, modified LDL activated platelets to a greater extent than n-LDL, suggesting different types of LDL-receptors. Their agonistic effect was inversely related to the fasting serum lipid profile, suggesting that blunting of platelet responses to LDL could represent a protective mechanism in hyperlipidemic patients.
Amyloid β-Protein Precursor-Rich Platelet Microparticles in Thrombotic Disease
Authors: Nomura Shosaku , Komiyama Yutaka , Miyake Tetsuya , Miyazaki Yasuhiko , Kido Hirofumi , Suzuki Masahiko , Kagawa Hideo , Yanabu Mutsumasa , Takahashi Hakuo , Fukuhara Shirou 
Published: July 2018

SummaryWe investigated the association of amyloid β-protein precursor (APP) and platelet derived microparticles in 20 normal controls and 91 patients with various diseases causing a thrombotic tendency. Compared with the controls, the mean percentage of APP-positive microparticles was significantly greater in the patients with cerebral infarction (39.1 ± 17.7%, p <0.001), diabetes (31.1 ± 12.6%, p <0.001), and uremia (30.1 ± 14.7%, p <0.01), but not in those with hypertension (8.2 ±6.3%, p = NS). Sixteen patients with cerebral infarction, 20 with diabetes, and 11 with uremia had microparticles with very high APP levels. In normal controls, 7.2 ± 3.7% of the microparticles were positive for P-selectin, while the percentage in cerebral infarction, diabetes, uremia, and hypertension was respectively 43.5 ± 15.1%, 40.0 ± 12.8%, 31.8 ±12.2%, and 11.6 ±7.3%. There was a significant correlation between P-selectin and APP positivity of microparticles. Our results suggest that microparticle APP may have a regulatory influence on coagulation abnormalities.
Homozygous Type I Protein C Deficiency in Two Unrelated Families Exhibiting Thrombophilia Related to Ala136→Pro or Arg286→His Mutations
Authors: Long G L , Tomczak J A , Rainville I R , Dreyfus M , Schramm W , Schwarz H P 
Published: July 2018

SummarySeparate single nucleotide mutations have been identified in two unrelated homozygous type I protein C deficient individuals suffering from thrombophilia. Each mutation, initially established by direct DNA sequencing of polymerase chain reaction amplification products, results in an amino acid substitution. The first mutation (PCClamart) results in an Ala136 to Pro substitution in the protein’s second epidermal growth factor-like domain. The second mutation (PCMtinchen) results in an Arg286 to His substitution in the serine protease domain. Comparison of the location of these two mutations and the relative conservation of the two regions in homologous vitamin K-dependent plasma proteins is consistent with the difference in severity of protein C deficiency and disease in the two individuals. Both mutations result in the abolition of a naturally occurring restriction endonuclease site, thereby allowing independent confirmation of the mutations and rapid and unambiguous genetic analysis of protein C deficiency in family members. In both families, the genetic analysis has proven useful in cases where an assignment of the protein C status based upon clinical laboratory measurements was either ambiguous or incorrect.
A Chromogenic Test to Determine the Procoagulant Phospholipids in Platelet-rich Plasma and Whole Blood
Authors: Wagenvoord R J , Hendrix H H , Kai Hu , Hemker H C 
Published: July 2018

SummaryWe have developed a chromogenic assay to measure the phospholipid-related procoagulant activity (PPA) in whole blood, or platelet-rich plasma. The test is based upon thrombin formation from prothrombin by prothrombinase and is designed in such a way that procoagulant lipids are rate limiting for the prothrombinase activity. In the chromogenic test PPA concentrations equivalent to 0-10 nM phospholipid vesicles containing 75% phosphatidyl choline (PC) and 25% phosphatidyl serine (PS) can be measured.The thrombin, which develops during the test, is measured with a chromogenic substrate. By the action of thrombin on this chromogenic substrate p-nitroaniline is liberated, which causes an increase in absorbance. Thrombin formed in the assay mixture activates the present platelets. This causes a linear increase of the velocity of thrombin generation during the test, i. e. a parabolic increase of product formation. For that reason the thrombin generation in time is characterized by two parameters, the basal PPA (PPA-B) of the original mixture and the increase in PPA due to platelet activation (PPA-A). To determine these figures the absorbency-data were fitted to parabolas. In most cases the contribution of PPA-A to the total amount of formed thrombin becomes considerable already after 30 s.Preliminary tests show that PPA-B activity in whole blood or platelet-rich plasma of patients with a thrombotic disorder is significantly higher than the activity of a control group of the same age.
Species Variability in Platelet and other Cellular Responsiveness to Thrombin Receptor-derived Peptides
Authors: Connolly Thomas M , Condra Cindra , Feng Dong-Mei , Cook Jacquelynn J , Stranieri Maria T , Reilly Christopher F , Nutt Ruth F , Gould Robert J 
Published: July 2018

SummaryThe aggregation of platelets from a variety of animal species in response to thrombin receptor-derived activating peptides was evaluated. A series of 14-(SFLLRNPNDKYEPF), 7-(SFLLRNP-NH2), 6-(SFLLRN-HN2) or 5-(SFLLR-NH2) residue peptides, the structures of which were based on the deduced amino acid sequence of the human thrombin receptor, promoted full aggregation of platelets in plasma from humans, African Green and Rhesus monkeys, baboons and guinea pigs at 4-50 μM depending on the peptide used. Platelets in plasma from rabbit, dog, pig, and hamster underwent a shape change but failed to aggregate in response to these peptides over 3 log units of peptide up to 800 μM, despite being fully responsive to human thrombin. However, because the receptor peptides induced shape change in the platelets from these non-aggregating species, they apparently can activate some of the intracellular signaling system(s) usually initiated by thrombin in these platelets. In contrast, platelets from rats did not undergo shape change or aggregate in response to the peptides. A 7-residue receptor-derived peptide based on the deduced amino acid sequence of the clone of the hamster thrombin receptor (SFFLRNP-N2) was nearly as efficacious as the corresponding human receptor-derived 7-residue peptide to promote aggregation of human platelets. However, the hamster peptide could not promote aggregation of hamster platelets in plasma at up to 800 μM peptide, while a shape change response was elicited. Platelets from rats, rabbits and pigs also did not aggregate in response to this peptide derived from the hamster thrombin receptor, but all species except the rat underwent a shape change. Longer 17-residue peptides derived from the sequences of the hamster or mouse thrombin receptors elicited aggregation of human platelets but no aggregation of the hamster platelets. In contrast, the human 14- and 5-residue and the hamster 7-residue thrombin receptor-derived peptides promoted mitogenesis of CCL39 cells, a hamster fibroblast cell line. Finally, the human 6-residue thrombin receptor-derived peptide promoted contraction of normal and de-endothelialized canine coronary artery rings, despite having no pro-aggregatory effect on canine platelets. Taken together, these results demonstrate that the thrombin receptor-derived peptides are able to mimic many, but not all, of the activating effect of thrombin in different tissues from multiple species. The heterogeneity of responsiveness to these peptides should be taken into account in future experiments designed to elucidate the mechanism of thrombin stimulation of platelets and other cells.
Factors Influencing the Reported Sensitivity and Specificity of Impedance Plethysmography for Proximal Deep Vein Thrombosis
Authors: Kearon Clive , Hirsh Jack 
Published: July 2018

SummaryA number of recent studies have found a considerably lower sensitivity of the IPG for proximal DVT than originally reported. We reviewed the literature to try and identify reasons for the between study differences in sensitivity and specificity of the IPG for proximal DVT. A number of biases were identified which may have inflated the sensitivity reported by some earlier studies including: repeated IPG testing prior to venography; inclusion of data from patients used to derive the IPG discriminant line in the final calculation of sensitivity; and inclusion of patients with a known abnormal IPG in the study population. In addition, there is emerging evidence that, at least in some centers, the sensitivity of the IPG may have decreased due to a shift in the spectrum of proximal DVTs to smaller clots. Furthermore, rates of conversion during serial follow-up are considerably higher for IPG than for venous ultrasound, suggesting that IPG conversion is often due to extension of small missed proximal DVTs rather than just extension of calf vein clots. As the smaller proximal DVTs which IPG is prone to miss are likely to be clinically less important than more extensive clots, it is unclear whether the recently reported drop in sensitivity of the IPG places patients at increased risk. IPG users need to be aware of its limitations, and we recommend that additional testing is performed in patients with a high clinical suspicion of DVT who have a normal IPG, as the negative predictive value of IPG may be unacceptable in these circumstances.
Demonstration of Platelet-Derived Microvesicles in Blood from Patients with Activated Coagulation and Fibrinolysis Using a Filtration Technique and Western Blotting
Authors: Andrè Holme Pål , Olav Solum Nils , Brosstad Frank , Røger Magnus , Abdelnoor Michael 
Published: July 2018

SummaryPlatelet vesiculation in vitro is correlated to platelet activation. It was therefore considered of interest to see if microvesicles (MV) are present in blood in clinical situations associated with platelet activation in vivo. Patients with both activated coagulation and fibrinolysis, implying that thrombin has been generated, suit such a purpose. Thus, the aim of this study was to investigate whether microvesicles could be detected in patients with activated coagulation and fibrinolysis, as diagnosed by the presence of soluble fibrin (positive ethanol gelation tests) and positive tests for fibrin degradation products (FDP). Platelet-rich plasma was prepared from citrated blood from patients (n = 22) and healthy controls (n = 32) matched as to age and sex. The intact platelets were removed from plasma by centrifugation. Any MV present were isolated from the platelet-free plasma by a filtration procedure, washed, solubilized in Triton X-100 and subjected to SDS-PAGE with Western blotting using a MAb against GPIIba as an indicator of the presence of microvesicles. All of the 22 patients showed the presence of microvesicles detectable by the content of GPIIba, whereas this could be observed in only 4 out of the 32 normal controls and then in small or trace amounts only. The presence of microvesicles among cell-derived material in the plasma of two of the patients was also confirmed by electron microscopy. To the best of our knowledge this is the first report on the presence of microvesicles in plasma from patients with both activated coagulation and fibrinolysis. Thus, the isolation of the microvesicles by the filtration technique allowed studies of the chemical composition of the microvesicles, and demonstrated the presence of microvesicles in situations where platelets are expected to have been activated in vivo and a tendency to thrombosis exists.
Markers of Hemostatic Activation in Affected Coronary Arteries during Angioplasty
Authors: Shammas Nicolas W , Cunningham Michael J , Pomearntz Richard M , Francis Charles W 
Published: July 2018

SummaryTo characterize the extent of early activation of the hemostatic system following angioplasty, we obtained blood samples from the involved coronary artery of 11 stable angina patients during the procedure and measured sensitive markers of thrombin formation (fibrino-peptide A, prothrombin fragment 1.2, and soluble fibrin) and of platelet activation ((3-thromboglobulin). Levels of hemostatic markers in venous blood obtained from 14 young individuals with low pretest probability for coronary artery disease were not significantly different from levels in venous blood or intracoronary samples obtained prior to angioplasty. Also, there was no translesional (proximal and distal to the lesion) gradient in any of the hemostatic markers before or after angioplasty in samples obtained between 18 and 21 min from the onset of the first balloon inflation. Furthermore, no significant difference was noted between angioplasty and postangioplasty intracoronary concentrations. We conclude that intracoronary hemostatic activation does not occur in the majority of patients during and immediately following coronary angioplasty when high doses of heparin and aspirin are administered.
Long-Term Stability Studies on the WHO IRP for Thromboplastin (Human Plain BCT/253)
Authors: Poller L , Pulford Jean , Stevenson K J , Cooper P , Gamble G , Thomson Jean M 
Published: July 2018

SummaryLong-term stability studies on the WHO second primary International Reference Preparation (IRP) for thromboplastin (human plain BCT/253) stored at ™20° C have been conducted for ten years.Three centres took part in the exercise using frozen normal and coumarinised plasma samples which were tested throughout. There has been no measurable change in the prothrombin time performance of the human plain IRP over the ten-year period. It can therefore be concluded that new IRP may continue to be calibrated against this preparation in accord with WHO recommendations.
Thrombin Regulation in Children Differs from Adults in the Absence and Presence of Heparin
Authors: Andrew Maureen , Mitchell Lesley , Vegh Patsy , Ofosu Frederick 
Published: July 2018

SummaryThe physiologic mechanisms that protect children from thromboembolic complications are not known. We investigated the regulation of thrombin in children because of its central importance to thrombosis. The capacity to generate thrombin in vitro (chromogenic assay) was decreased by 26% in plasmas from children (1-16 yrs; n = 102) compared to adults ([20-45 yrs; n = 20; p <0.001]). The addition of purified prothrombin to plasmas from children increased thrombin generation to adult values. The capacity of plasmas to inhibit 125I-α-thrombin was increased by 21% in children compared to adults (p = 0.020), with significantly more thrombin complexed to a2-macroglobulin (α2M) in children.When DVT occur in children, adult guidelines for heparin therapy are used. At low heparin concentrations (0.1 and 0.2 U/ml), thrombin generation was decreased by 30% in children compared to adults (p <0.001). At high heparin levels (0.4 U/ml), thrombin generation was negligible in all plasmas. ATIII inhibited over 95% of thrombin in all plasmas in the presence of heparin.In summary, thrombin regulation differs in children from adults and may protect children from thromboembolic complications. When DVT do occur, heparin requirements may differ in children compared to adults.
Fibrinolytic Activity in Blood Is Distributed over a Cellular and the Plasma Fraction which Can Be Modulated Separately
Authors: van Giezen J J J , Chung-A-Hing J E , Vegter C B , Bouma B N , Jansen J W C M 
Published: July 2018

SummaryBlood fibrinolytic activity is mediated by plasma and cellular components. We have studied blood fibrinolytic activity in different species and investigated the distribution pattern in rats after modulation with PAF, dexamethasone, or retinoic acid. Whole blood and plasma activity were measured in an assay system using human or endogenous fibrin as substrate. When human fibrin was used as substrate marked species differences in distribution of fibrinolytic activity were observed. In rat and murine blood most fibrinolytic activity was associated with the plasma fraction (70% and 50% respectively) while in human and canine blood the plasma fraction contained only 30% of the blood fibrinolytic activity. When endogenous fibrin was used as substrate the distribution pattern of fibrinolytic activity in rat blood changed dramatically. Less than 25% of the blood fibrinolytic activity was now present in the plasma fraction.The fibrinolytic system was further investigated in rats using specific inhibitors of proteolytic activity. Blood fibrinolytic activity could be inhibited for 33% by antibodies raised against t-PA and 60% inhibition was obtained in the presence of amiloride. No significant effect of elas-tinal (an inhibitor of elastase) could be detected. Plasma fibrinolytic activity was not affected by these inhibitors. The fibrinolytic activity in plasma could be enhanced about 100-fold after i. v. PAF administration (10 μg/kg). This extra fibrinolytic activity could be fully blocked by antibodies raised against t-PA. Oral administration of dexamethasone or retinoic acid affected blood fibrinolytic activity by modulating selectively the activity mediated by the cellular fraction. Dexamethasone treatment (1 mg/kg) resulted in a 59% decrease of this fibrinolytic activity. Retinoic acid treatment (3 mg/kg) resulted in a 69% increase of the fibrinolytic activity in this phase. Both compounds affected selectively the t-PA activity.We conclude that 1) the plasma as well as the cellular fraction contribute to the blood fibrinolytic activity; 2) the plasma derived fibrinolytic activity as such is a minor part of the total whole blood fibrinolytic activity (the mouse is an exception); 3) the rat blood fibrinolytic activity is evoked by u-PA (two third) and t-PA (one third) mediated processes; 4) the blood fibrinolytic activity can be modulated, in contrast to the plasma activity as such, by retinoic acid or dexamethasone; 5) the plasma fibrinolytic activity is subject to modulation by compounds which evoke a direct PA increase.
In Vitro Stability of a Tissue-Type Plasminogen Activator Mutant, BM 06.022, in Human Plasma
Authors: Rijken D C , Groeneveld E , Barrett-Bergshoeff M M 
Published: July 2018

SummaryBM 06.022 is a non-glycosylated mutant of human tissue-type plasminogen activator (t-PA) comprising only the kringle-2 and proteinase domains. The in vivo half-life of BM 06.022 antigen is 4- to 5-fold longer than that of t-PA antigen. The in vitro half-life of the activity of BM 06.022 at therapeutic concentrations in plasma is shorter than that of t-PA. In this study the inactivation of BM 06.022 in plasma was further investigated.Varying concentrations of BM 06.022 were incubated in plasma for 0-150 min. Activity assays on serial samples showed a dose-dependent decline of BM 06.022 activity with a half-life from 72 min at 0.3 μg/ml to 38 min at 10 μg/ml. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) followed by fibrin autography showed the generation of several BM 06.022-complexes. These complexes could be completely precipitated with antibodies against Cl-inactivator, α2-antiplasmin and α1-antitrypsin.During the incubation of BM 06.022 in plasma, plasmin was generated dose-dependently as revealed by varying degrees of a2-anti-plasmin consumption and fibrinogen degradation. SDS-PAGE and immunoblotting showed that single-chain BM 06.022 was rapidly (i. e. within 45 min) converted into its two-chain form at concentrations of 5 μg/ml BM 06.022 and higher.In conclusion, BM 06.022 at therapeutic concentrations in plasma was inactivated by Cl-inactivator, a2-antiplasmin and a j-antitrypsin. The half-life of the activity decreased at increasing BM 06.022 concentrations, probably as a result of the generation of two-chain BM 06.022 which may be inactivated faster than the single-chain form.