bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Inhibitory Actions of Prostacyclin and a New Prostacyclin Analogue on the Aggregation of Human Platelet in Whole Blood
Authors: Saniabadi A.R. , Belch J.J.F. , Lowe G.D.O. , Barbenel J.C. , Forbes C.D.
Published: April 2009

Prostacyclin (PGI2), an unstable endogenous prostanoid, is a potent vasodilator and inhibitor of platelet aggregation. The use of exogenous PGI2 as an antithrombotic agent is limited by its chemical instability and lack of dissociation between its vasodilatory and antithrombotic actions. Iloprost (ZK36374) is a recently developed, chemically stable, carbacyclin analogue of PGI2. Preliminary evaluation studies have shown a significant dissociation between vasodilatory and antithrombotic actions of Iloprost. We have compared the effects of PGI2 and Iloprost on platelet aggregation in human whole blood. Platelet aggregation was induced by ADP (4 μM), adrenaline (Adr, 0.4 μM) and arachidonic acid (AA, 0.4 mM). Aggregation was quantified as a fall in the number of single platelets counted using the Clay Adams Ultra Flo 100 whole blood platelet counter. In the absence of any PGI2 or Iloprost, each aggregating agent induced up to an 80% fall in the number of single platelets counted. When blood was pre-incubated with PGI2 (1–6 nM) or Iloprost (1–6 nM), aggregation responses to all three aggregating agents were inhibited in a dose-dependent manner. Iloprost was equipotent to PGI2 against ADP-induced aggregation but was more potent than PGI2 against Adr- and AA-induced aggregation. It is concluded that Iloprost, as a chemically stable PGI2 analogue, may be superior to PGI2 as an antithrombotic agent.
Increase of Nonplasmin Fibrinolytic Activity in the Lung and Spleen of Streptozotocin-Induced Diabetic Rats
Authors: Okamoto Utako , Nagamatsu Yoko , Yamamoto Junichiro , Ikeda Sayoko , Kubota Akira
Published: April 2009

In streptozotocin-induced diabetes in rats, nonplasmin fibrinolytic activity was found to be significantly increased in the lung and spleen, but not in the liver and kidney. The plasminogen-activator activities, either soluble or insoluble, were almost simultaneously increased in the lung, suggesting the possible release of plasminogen-activator from the lung to the blood. It seems likely that plasminogen-activator of the usual type and nonplasmin protease are also involved in thrombotic disorders in the experimental diabetes.
Measurement of Factor VIII Procoagulant Antigen in Normal Subjects and in Hemophilia A Patients by an Immunoradiometric Assay and by an Enzyme-Linked Immunosorbent Assay
Authors: Hellstern Peter , Miyashita Chieko , Köhler Michael , von Blohn Gerhard , Kiehl Ralf , Biro Geza , Schwerdt Holger , Wenzel Ernst
Published: April 2009

Factor VIII coagulant antigen (FVIIl·Ag) and FVIII coagulant activity (FVIIl·C) were measured in 102 healthy individuals, in 5 hemophilia A carriers and in 21 hemophilia A patients before and after infusion of heat-treated high-purity FVIII concentrates. Factor VIIl·Ag was determined by a solid-phase micro enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies and by a conventional solid-phase immunoradiometric assay (IRMA). Factor VIII:C was assessed using a one-stage assay. The micro ELISA was decidedly more precise than the IRMA. There was a close correlation between the results obtained by the three assays in the plasma of healthy subjects and in hemophilia A carriers. After transfusion of FVIII concentrates to hemophilia A patients, the FVIIl·Ag recoveries were significantly lower than the FVIIl·C recoveries and the biological half-life of FVIIl·Ag was significantly shorter than for FVIIl·C. The calculated half-life of FVIIl·C was longer than in any previous study.
Von Willebrand Factor Fragment in Type IIA von Willebrand’s Disease: Demonstration of Two Different Forms of Fragments
Authors: Takahashi Hoyu , Tsukada Tsuneyasu , Tatewaki Wataru , Hanano Masaharu , Sanada Masayoshi , Shibata Akira
Published: April 2009

A fast-migrating precipitin peak which showed a reaction of partial immuno-chemical identity with the major von Willebrand factor (vWf) component was detected by crossed immunoelectrophoresis in agarose gel in plasma but not in platelets from a patient with type IIA von Willebrand’s disease (vWD). Another patient undergoing urokinase therapy had a vWf fragment in plasma which was antigenically cross-reactive with the major vWf component. When plasma from both patients was mixed and electrophoresed together in the first dimension, two fast-moving precipitin arcs were demonstrated in the second dimension. These data indicate that two different kinds of vWf fragments can be generated in vivo.
Turbidimetric Evaluation of the Impact of Albumin on the Structure of Thrombin-Mediated Fibrin Gelation
Authors: Carr Marcus E.
Published: April 2009

Recent studies have reported an interaction of albumin with polymerizing fibrin, resulting in a narrowing of gel fibers. It has been postulated that albumin interacts with the E domain resulting in delayed and thus altered polymerization. Utilizing turbidity techniques, the impact of human albumin on gels of human fibrin, clotted with human thrombin, was studied. The addition of albumin, at concentrations from 3 to 30 µM, to 1 mg/ml fibrin gels produced less than a 10% change in either the kinetics of turbidity increase or the subsequent fiber mass-length ratio. For a given calcium concentration, saturation of albumin’s calcium-binding capacity by prior dialysis ablated even these small effects. Given these findings, it seems unlikely that albumin imposes a physiologically significant influence on fibrin polymerization. Structural changes secondary to albumin-mediated enhancement of factor XIII activity remain a possibility.
Comparative Study on the Effects of a Low Molecular Weight Heparin (CY 216) and Standard Heparin in Low Dosage on Experimental Venous Thrombosis
Authors: Doutremepuich Ch. , Bousquet F. , Gestreau G.L. , Toulemonde F. , Bayrou B.
Published: April 2009

In a venous thrombosis model in the rat obtained by ligation of the inferior vena cava, the effects of standard heparin and CY 216, a low molecular weight heparin fraction, are compared. At a dosage of less than 2 mg/kg b.w. CY 216 is an effective antithrombotic, whereas standard heparin is not.
Protamine-Induced Platelet Aggregation and Clotting Investigated by Ultrasound
Authors: Machi Junji , Sigel Bernard , Feinberg Harold
Published: April 2009

Using high-resolution real-time ultrasound to monitor platelet aggregation and plasma clotting, the effect of protamine on platelets was evaluated in a dynamic system of plasma in vitro. Protamine induced platelet aggregation preceding plasma clotting at both low (1.6 s-1) and moderate (22.6 s-1) shear rates. The onset of aggregation and clotting was accelerated at the higher shear rate. Low-shear clots were heterogeneous on ultrasonic imaging, whereas moderate-shear clots were more densely homogeneous. Protamine-induced platelet aggregation was reversed by additional heparin. Pretreatment of plasma with pros-tacyclin prevented protamine-induced aggregation, but clot formation occurred. However, such clots were less echogenic. EGTA and hirudin inhibited both aggregation and clotting. Our ultrasonic aggregometry showed that platelet aggregation was induced by protamine before clots formed, and that not only shear rate but platelet activation might affect the rate and composition of plasma clots.
Tumor Interaction with Vascular Endothelium
Authors: Al-Mondhiry Hamid , McGarvey Virginia
Published: April 2009

Clinical and experimental observations suggest that tumor-induced endothelial cell (EC) injury may be one of several initial events in the establishment of tumor metastases. This work investigates tumor-induced EC injury and the interaction between tumor-damaged EC and platelets. We used cultured bovine EC and extracts of four cultured human malignancies. EC injury was assessed by 51Cr and lactic dehydrogenase (LDH) release. Incubation of EC with melanoma, breast carcinoma or lung carcinoma caused significant LDH and 51Cr release, whereas colon cancer seemed ineffective. Increased adhesion of platelets to tumor-injured EC was noted. These observations indicate that certain varieties of tumor cause EC injury. Adhesion of platelets to tumor-injured EC results in the formation of platelet-tumor thrombi at the endothelial surface, an event that may initiate tumor invasion of the vessel wall.
Severe von Willebrand’s Disease: SDS Agarose Multimer Analysis
Authors: Redaelli Rosaria , Pezzetti Laura , Caimi Teresa , Baudo Francesco , de Cataldo Francesco
Published: April 2009

In severe von Willebrand’s disease (vWD), the multimeric analysis of von Willebrand factor (vWF) has been hindered by the low content of the protein although different patterns have been observed by radiocrossed immunoelectrophoresis (RCIE). Cryoprecipitate and vWF concentrate were obtained from the plasma of a severe vWD patient, that on RCIE had only the more anodic forms. The sodium dodecylsulfate (SDS) agarose analysis evidences the presence of the main bands, a relative increase of the smaller forms and a lesser definition of some minor bands. These findings suggest the possibility of structural abnormalities in severe vWD. The study of cryoprecipitates could be a means to evidence the presence of multimers and the extent of the eventual pattern variability.
Antithrombin III Metabolism in Two Patients with a Nephrotic Syndrome Caused by Minimal Chain Nephritis and Primary Amyloidosis
Authors: Drijfhout Hendrik H. , Knot Eduard A.R. , ten Cate Jan W.
Published: April 2009

The metabolism and urinary excretion of 125I antithrombin III (AT III) was investigated in 2 patients with a nephrotic syndrome caused by minimal chain nephritis and primary amyloidosis, and acquired deficiency of AT III. Increased AT III catabolism was observed in both patients, even after correction for urinary protein loss. Increased AT III catabolism was due to increased influx from the extra- to the intravascular compartment in 1 patient, and to an increased fractional catabolic rate in the other patient who developed later a pulmonary embolism. Analysis of urine samples revealed biologically inactive whole AT III molecules and biologically as well as antigenically inactive fragments, respectively, whereas daily plasma gel filtration showed intact radioactive AT III. These observations reject the hypothesis that AT III deficiency in nephrotic patients is only due to urinary loss of AT III.
Relationship between Elevated Fibrinopeptide A Levels and Alpha-2-Antiplasmin
Authors: Marongiu F. , Mulas G. , Mamusa A.M. , Mameli G. , Marassi Giua , Tronci M.B. , Cambuli A.B. , Acca M.R. , Balestrieri A.
Published: April 2009

In order to investigate whether α2-antiplasmin (α2-AP) levels may be related to thrombin activity, we measured α2-AP and fibrinopeptide A (FPA) in 51 patients with clinical conditions frequently associated with increased thrombin activity. The diagnoses were: atherosclerotic disease, chronic inflammatory disease and hematological neoplastic disease. A significant negative correlation was found between α2-AP and FPA (p < 0.01). When patients were divided into three subgroups on the basis of their FPA levels, a significant reduction in α2-AP was found in patients with the highest FPA concentration ( > 9 ng/ml). Accordingly, a significant negative relationship between α2-AP and FPA was found only in this subgroup (p < 0.01). Our data suggest that the partial consumption of α2-AP in patients with elevated FPA levels may reflect a subclinical fibrinolysis activation secondary to increased thrombin activity.
Revised Standardization Method of the One-Stage Prothrombin Time
Authors: Korsbrekke Knut , Talstad Ingebrigt
Published: April 2009

The revised ratio method which is recommended for standardization of the one-stage prothrombin time, presumes that identical regression lines exist between clotting times of abnormal and normal plasma. A modification is proposed which corrects for possible deviation of the mean clotting time of normal plasma from the regression line between clotting times of abnormal plasma. The modified revised ratio method is theoretically preferable and does not need the restrictions in calibration which are recommended for the revised ratio method.
The Effect of Exercise on Thrombin and Plasmin Generation in Middle-Aged Men
Authors: Small M. , Simpson I. , McGhie I. , Douglas J.T. , Lowe G.D.O. , Forbes C.D.
Published: April 2009

Plasma levels of Bβ15-42 peptide and fibrinopeptide A (FPA) were measured as indicators of plasmin-mediated fibrin(ogen)olysis and thrombin activity of fibrinogen in 34 middle-aged men, at rest and following a standard exercise test. In the group as a whole no significant changes in Bβ15-42 or FPA were noted after exercise. When the group was subdivided into men with (n = 20) and without (controls n = 14) coronary heart disease, exercise-stimulated thrombin and plasmin generation was found only in the control group who exercised for a significantly longer duration. The rise in Bβ15-42 was related to both the intensity and duration of exercise. Similar increases in plasma fibrinolytic activity (fibrin plate) occurred in both groups and no other differences in the components of the fibrinolytic system (plasminogen, α2-antiplasmin, fibrin degradation product) were noted either after exercise or between the groups. Exercise in normal middle-aged men is associated with modest thrombin and plasmin activation.
New Aspects of Blood Vessel Growth: Tumor and Tissue-Derived Angiogenesis Factors
Authors: Presta Marco , Rifkin Daniel B.
Published: April 2009

Angiogenesis factors have been recently purified from both tumors and nonneoplastic tissues. The biological properties shown by these factors in vivo and on cultured endothelial cells will be discussed.
Role of the Coagulation System in Tumor-Cell-Induced Platelet Aggregation and Metastasis
Authors: Cavanaugh Philip G. , Sloane Bonnie F. , Honn Kenneth V.
Published: April 2009

The ability of tumor cells to initiate coagulation and subsequent platelet aggregation is believed to facilitate the metastatic process. The mechanism by which tumor cells initiate thrombotic alterations is unclear. We have purified a plasma membrane protein platelet aggregating activity/procoagulant activity (PAA/PCA) from several rodent tumors which initiates the coagulation of homologous plasma and aggregation of homologous platelets by a mechanism independent of factor VII. This protein does not possess any proteinase activity; however, its activity is dependent upon the presence of factor X. In addition, PAA/PCA requires reconstitution with phospholipid for expression of activity. These results suggest that tumor cells express a unique protein which possesses procoagulant activity resulting in thrombin generation. Thrombin is responsible for subsequent tumor-cell-induced platelet aggregation.
Different Expression of Procoagulant Activity in Macrophages Associated with Experimental and Human Tumors
Authors: Semeraro N.
Published: April 2009

Mononuclear phagocytes, an integral part of the lymphoreticular infiltrate of human and experimental tumors, might contribute to fibrin deposition within malignant tissues through the production of procoagulant activity (PCA). Recent studies in different types of experimental tumors and in some cancer patients indicate that the functional status in terms of PCA of mononuclear phagocytes at ‘peripheral’ sites is not the same as that of macrophages at the tumor site (tumor-associated macrophages, TAM). Peripheral blood monocytes and/or peritoneal macrophages from V2-carcinoma-bearing rabbits and from mice bearing different types of tumors, like cells from normal animals, have low levels of basal PCA and are able to respond with a marked increase in PCA to in vitro stimulation. Likewise, in patients with primary lung cancer, pulmonary alveolar macrophages (PAM) obtained from the contralateral side of the neoplasm and blood monocytes behave essentially as cells from normal individuals. In contrast, profound changes in PCA have been found in TAM. In some experimental tumors and in a number of the patients, macrophages taken at the tumor site express high levels of basal PCA, which most probably reflect in vivo activation. Local activation of macrophages for PCA production might contribute to fibrin deposition at the tumor site. In the other experimental tumors studied and in the remaining patients, not only have macrophages low basal PCA but they also fail to respond to various stimulants in vitro. Although the mechanisms underlying these changes and their pathophysiological significance remain to be established, it is apparent that neoplastic growth may modulate the expression of macrophage PCA at the tumor site. PCA may be a useful parameter to better characterize the functional status of macrophages associated with tumors.
AIDS and Haemophilia
Authors: Rosendaal Frits R. , Smit Cees , Varekamp Inge , Brocker-Vriends Annette , Suurmeijer Theo P.B.M. , Briët Ernest
Published: April 2009

More than 75% of all Dutch haemophiliacs participated in a mail survey that included a section on acquired immunodeficiency syndrome (AIDS). Although no cases of haemophilia-related AIDS had been reported in the Netherlands at the time of our survey, the threat of AIDS had caused considerable anxiety among Dutch haemophiliacs. This had led almost a third of the patients to change their therapy schedules. These changes were mostly not beneficial and possibly counterproductive, since they were not likely to reduce the risk of human immunodeficiency virus (HIV) infection. Measures that were advised to prevent HIV transmission, such as the use of condoms, were seldom carried out, even by the 17% seropositive individuals. We conclude that an increase in the informational efforts towards the patients is called for to avoid ill-advised treatment changes and to enhance preventive behaviour.
Experimental Hemarthrosis in Dogs: Progressive Synovitis Monitored with Technetium-99m Pyrophosphate Joint Imaging
Authors: Tessier John E. , Salimi Zarrin , Restrepo Guillermo L. , Samuels Larry D. , Joist Heinrich
Published: April 2009

We examined the time course of the development of hemorrhagic synovitis in response to repeated autologous blood injections into knee joints in mature dogs and the possible usefulness of joint imaging with technetium-99m pyrophosphate (Tc99m-PYP) in monitoring the early response of synovium to blood. Experimental hemarthrosis was induced in dogs by twice weekly injection of autologous blood into the knee joints. Sequential examination of the synovium at monthly intervals over a period of 12 weeks revealed early inflammatory cell infiltration and capillary neovascularization with eventual replacement of the normal fatty synovium by dense fibrous tissue. Serial Tc99m-PYP joint images demonstrated a progressive increase in isotope accumulation in the knees during the course of the study. Further isotope accumulation was observed after CO2 laser synovectomy. During the 24-week course of the entire study, no changes in joint cartilage or bone were observed by gross inspection or radiologic and light-microscopic examination. The findings indicate that the progressive proliferative, inflammatory, fibrotic changes in joint synovium associated with experimental hemarthrosis in dogs may be noninvasively and semiquantitatively assessed with the use of Tc99m-PYP scintigraphy. Evidence is also presented that the intensity of Tc99m-PYP joint accumulation (immediate static images) may not readily reflect synovial vascularity or synovial tissue mass.
Influence of Hydroxyl Radical Scavengers on Platelet Function
Authors: Violi F. , Ghiselli A. , Iuliano L. , Alessandri C. , Cordova C. , Balsano F.
Published: April 2009

The influence of four hydroxil radical (OH•) scavengers on platelet function was investigated. OH• scavengers inhibited ADP, collagen, arachidonic acid, PAF-induced platelet aggregation, and platelet cyclooxygenase pathway activation, which was studied by evaluating platelet malondialdehyde and serum thromboxane A2 formation. The latter was not affected by superoxide dismutase, catalase, or metal ion chelants such as desferioxamine or DETAPAC. The detection of deoxyribose degradation by stimulated platelets suggested that platelets produce OH•. This study shows that activated platelets produce free radicals and that antioxidant agents such as OH• scavengers inhibit platelet function.
Influence of the Fibrin(ogen) Degradation Product Fragment D on the Monolayer Integrity of Cultured Vascular Endothelial Cells
Authors: Delvos Ulrich , Müller-Berghaus Gert
Published: April 2009

The effect of purified fibrin(ogen) degradation product fragment D on cultured bovine aortic endothelial cells has been investigated. Binding to the cells was studied using purified radiolabelled fragment D and assessment of its recently postulated deleterious action was made by three different approaches: release of 51Cr from prelabelled cell layers, uptake of 3H-adenine by the cultivated cells as well as determination of residual cell number after exposure to various concentrations of fragment D were carried out. None of these methods applied was able to detect any harmful effect of the fragment on endothelial cell integrity and function in vitro. Neither could a specific interaction of the protein with the cultured cells be established. Even huge amounts of fragment D (1 mg/ml) exposed to the cells over 20 h did not reveal any alterations in the typical monolayer morphology. Thus, fragment D, which is generated in large amounts during systemic fibrinolytic treatment, does not exert any perturbation on cultured vascular endothelial cells as had previously been proposed.
Comparison of Kinetic Parameters of the Activation of Glu-Plasminogen by Tissue Plasminogen Activator Obtained from Various Sources
Authors: Takada Akikazu , Sugawara Yoshiaki , Takada Yumiko
Published: April 2009

Kinetic analyses were made for the activation of Glu-plasminogen (Glu-Plg) by tissue plasminogen activator (t-PA) obtained from various sources. We compared kinetic parameters for three t-PA preparations. t-PA(M) was obtained from cultured melanoma cell line, and t-PA(W) and t-PA(TD) were obtained from cells with recombinant DNA. t-PA(W) had two chains whereas t-PA(TD) had one chain. Although values of kinetic parameters were different in the three t-PA preparations, there were following general tendencies. The presence of catalytic amounts of fibrin resulted in a decrease in Km, whereas the presence of larger amounts of fibrin resulted in an increase in kcat with a slight decrease in Km. The presence of fibrinogen also enhanced the activation of Glu-Plg by t-PA with an increase in kcat and without change in Km. When the effects of fragment D or E were compared, the presence of increasing amounts of E resulted in an increase in kcat, but the presence of increasing amounts of D resulted in an increase in kcat and a decrease in Km. The results suggest that roles of D and E domains of fibrin may be different in the enhanced activation of plasminogen by t-PA.
Fatty Streaks and Fibrous Plaques in Human Aorta Show Increased Plasminogen Activator Activity
Authors: Smokovitis A. , Kokolis N. , Alexaki-Tzivanidou E.
Published: April 2009

Marked changes of the plasminogen activator activity, plasmin inhibition, and plasminogen activator inhibition were found in fatty streaks and fibrous plaques compared to the normal intima of the human aorta. Plasminogen activator activity and plasmin inhibition showed the following pattern: fibrous plaques > fatty streaks > normal intima. Plasminogen activator inhibition showed the opposite pattern: normal intima > fatty streaks > fibrous plaques. The tissue-type, but not the urokinase-type, plasminogen activator was detected immunologically.
Differences between Beige and bg/+ Mice in the Disruption of Plasma Proteinase Regulation in the Tumor-Bearing State or following Corynebacterium parvum Treatment
Authors: Hart David A.
Published: April 2009

Mice bearing the B16 melanoma or treated with Corynebacterium parvum develop elevated levels of plasma neutral proteinase activity. Similar experiments carried out with C57BL/6-bg/bg (beige) mice, which are genetically deficient in polymorphonuclear neutrophil (PMN) proteinases, revealed that such mice develop significantly diminished elevation in plasma proteinase activity compared to C57BL/6-bg/+ mice. Lysates of C. parvum elicited PMN from beige mice contained approximately 80% less neutral proteinase activity as did lysates of PMN from bg/+ mice. These results indicate that host cells, such as PMN, may become activated during the tumor progression, or following C.parvum treatment, causing degranulation and a subsequent elevation in plasma proteinase levels. If such an interpretation is correct, then this phenomenon may be the murine corollary to what has been observed in patients with certain inflammatory diseases or tumors.
Plasminogen: A Brief Introduction into Its Biochemistry and Function
Authors: Miyashita C. , Wenzel E. , Heiden M.
Published: April 2009

Human plasminogen is a β-globulin (2 % carbohydrate, molecular weight 90 KD), which in its native form has NH2-terminal glutamic acid (Glu-plasminogen) whose primary structure is known (31, 37, 38). From human plasma plasminogen can easily be isolated by affinity chromatography techniques (10, 25, and Table 1). Plasminogen is synthesized in many organs. The production site of the zymogen may be the liver (21), the eosinophiles (3) or the kindney (15). The plasma-plasminogen level is low in newborns (22) and even lower in the premature infant (2). In healthy adults it is found in plasma or serum in a concentration of 200 mg/l (= 2 μM, 22, 39). The half-life of the native (Glu-) plasminogen is 2.24 ± 0.29 days (6). Two types of Glu-plasminogen occur in human plasma, which differ in their carbohydrate composition as well as in their content of sialic acid. Genetic variants (see Mayr, 3.1.); of plasminogen have been reported (16) after isoelectric focusing of human plasma in polyacrylamide gels. Three patterns were found, two completely different and the third most likely a mixture of the other two. Characteristical functional properties of plasminogen are related to its molecular structure, e.g. its in vivo specificity for fibrin in contrast to the fairly unspecific in vitro activity of plasmin. Glu-plasminogen is easily converted by limited plasmic digestion to modified forms with NH2-terminal lysine, valine or methionine (35, 36), which are commonly designated Lys-plasminogen” (26) displaying a plasma half-life time of 0,8 days (6). Lys-plasminogen forms are easily converted to plasmin which results in the formation of two-chain molecule (Lys-plasmin) from the single-chain monomer (zymogen).
Standardization of Plasminogen Assays
Authors: Gaffney P.J.
Published: April 2009

Like a number of the components of the fibrinolytic and coagulation systems, plasminogen (plgn) is a multifunctional molecule. As a proenzyme, a number of its activities such as its binding to fibrin, histidine-rich glycoprotein (HRGP) and α2-antiplasimn (AP) are expressed while its major enzymatic activity remains unexpressed. This latter activity has been used as a yardstick of plasminogen potency, despite the fact that no such activity resides in the native plasminogen molecule. Assay procedures usually involve the activation of the plasminogen to plasmin using an activator such as streptokinase (SK) or urokinase (UK) and a major problem involves the establishment of a properly-timed plasminogen-activator ratio to fully express the plasminogen as the active enzyme plasmin (Gaffney, P.J. et al. Activation of plasminogen as a feature of its assay. Haemostasis 1977, 6, 72–78). Substrates such as casein, fibrinogen and fibrin have been used to assess the plasmin activity developed while more recently the tripeptide chromogenic substrate S-2251 has been successfully used. These assays have been standardised using a reference preparation of the active enzyme, plasmin, and both a 1st and 2nd International Reference Preparation (IRP) have been established. These IRP’s differed in that the fibrin binding kringle-structures were missing in the 1st IRP yielding differing fibrinolytic and chromogenic activities (Philo, R.D. and Gaffney, P.J. Plasmin potency estimates. Influence of substrate used in assay. Thrombosis and Haemostasis 1981, 45, 107–109). Activation procedures of plasminogen and subsequent assays of plasmin using a variety of substrates have been recently superseded by an assay which involves the formation of a plgn-SK complex which complex has an active site which hydrolyses the chromogenic substrate S-2251. This avoids the problems highlighted above involved in measuring plasminogen activity at the optimum stage during activation. While plasmin standards have been suitable for the standardisation of plasminogen when it is measured by activation-based procedures, a British Standard for glutamic acid-plasminogen has now been established in order to standardise the plgn-SK assay (Gaffney, P.J. and Curtis, A.D. The establishment of a standard for plasminogen (glu-type). Thrombosis and Haemostasis 1984, 51, 376–378). The calibration of this standard using the 2nd IRP for plasmin and the value of this standard in the measurement of plasminogen in plasma is discussed.
Genetic Polymorphism of Plasminogen
Authors: Mayr W.R.
Published: April 2009

By isoelectric focusing in a pH range of pH 3.5 – 9.5 or of pH 5–8, and by using a functional or an immunological detection, a genetic polymorphism of plasminogen can be demonstrated. In Caucasoids, 2 common alleles – PLG*A (frequency 0.67) and PLG*B (frequency 0.30) – as well as several rare variants (sum of their frequencies 0.03) exist. Systematic studies on the functional activity of the various plasminogen gene products should be performed in order to analyse whether or not a difference of plasminogen activity can be observed amongst the possible phenotypes and in order to see whether or not the various plasminogen phenotypes have any clinical significance.
Intermittent Plasminogen-Streptokinase Treatment of Deep Vein Thrombosis
Authors: Kakkar V.V. , Scully M.F.
Published: April 2009

Thrombolytic therapy has been used for treating patients suffering from a variety of clinical disorders including patients suffering from extensive venous and arterial thrombosis. This paper describes a combined approach to lytic therapy consisting of administration of small doses of streptokinase in combination with the infusion of plasminogen. The rationale for this approach is based on recent observations that additional plasminogen will be absorbed into preformed thrombi, rendering them more susceptible to lysis in the presence of activators. Forty-four patients who presented with symptoms and signs of acute or sub-acute deep vein thrombosis (DVT) confirmed by phlebography, were included in this study. Group I: 15 consecutive patients received an infusion of 600,000 units of SK dissolved in 50 ml of physiological saline over a period of half and hour. On the subsequent 4 days, a dose of 300,000 units was given twice daily. Group II: 29 consecutive patients received 60 to 90 mg of pre-treated plasminogen dissolved in 50 ml of saline given intravenously over 30 min. and followed by same dosage regimen of SK. Blood samples were taken at varying intervals to assess changes in the haemostatic parameters. These were analysed for levels of α2-antiplasmin, antithrombin III, fibrinogen, plasminogen, fibrinogen and degradation products, fibrinolytic activity and levels of activator complex. Findings observed will be presented. Phlebograms were performed before starting treatment and were repeated at the end of 5 days when the treatment had finished. In Group I – (15 patients) – thrombi remained virtually unchanged in 12 out of 15 patients receiving streptokinase infusion; in 3 (20 %) there was partial but extensive lysis. In contrast, in Group II – (29 patients) – in 16 (55 %) of 29 patients receiving plasminogen and streptokinase infusion, complete lysis of thrombi was obtained. Seven (24 %) showed extensive clearance of venous tree while in remaining 6, thrombi virtually remained unchanged. The results in this study support the growing evidence that intermittent streptokinase therapy in combination with plasminogen infusion has advantages over the classical approach.
Relation of Antifactor Xa Activity of Heparins and Antithrombotic Efficacy
Authors: Harenberg J.
Published: April 2009

In the present paper some of the characteristics of the pharmacodynamics of low-molecular-weight (LMW) heparin and the importance of the inhibition of the factor Xa are outlined. In summary, there is some evidence that the inhibition of factor Xa mediated fibrin formation and antithrombotic effects. However, there is a lot of experimental evidence that heparin and LMW heparins induce antithrombotic effects by releasing compounds from vascular endothelium, too. Thus, distinct interactions of heparin and LMW heparins with the cellular compounds of the blood may modulate the antithrombotic and hemorrhagic capacities.
Effects of Unfractionated and Fractionated Heparin on Platelet Function
Authors: Heinrich D. , Görg T. , Schulz M.
Published: April 2009

Heparin-induced alterations of platelet function have repeatedly been reported over the last 30 years. The development of low-molecular-weight (LMW) heparin fractions prompted us to compare the effect of unfractionated (UF) heparin and LMW heparin on platelet function. Heparin was applied intravenously to healthy volunteers in a dose of 100 U (antifactor Xa)/kg body weight. Sequential evaluation of platelet function ex vivo confirmed that UF heparin may activate platelets in vivo. Studying the ADP-induced fibrinogen binding to platelets in vivo, we were able to show that the effect of heparin on platelets is antibody- and antithrombin-III-independent. LMW heparin fractions in general exhibit a reduced platelet activating activity although there are differences between the LMW heparin fractions available. The stimulating effect of LMW heparin on platelets disappears below a mean molecular weight of 3,000 daltons.
Effect of Low-Molecular-Weight Heparins on Laser-Induced Thrombus Formation in Rat Mesenteric Vessels
Authors: Weichert W. , Breddin H.K.
Published: April 2009

Laser-induced thrombi have been frequently produced in rat mesenteric vessels to investigate the effect of antithrombotic drugs. We have tested low molecular heparins in comparison to unfractionated heparin. The investigations were carried out on male Wistar rats weighing 200–300 g; the animals were anesthetized with pentobarbital sodium (Nembu-tal®) 60 mg/kg i.p. Vascular lesions were induced with a Coherent CR-2 supergraphite ion laser (argon laser) mounted on a Leitz Orthoplan microscope. An intestinal loop was spread on a self-constructed object stage, mounted on the microscope table. The laser beam was directed through the optical path of the microscope on small mesenteric vessels in the fat-free portion of the mesentery. For the evaluation of thrombus formation the number of laser injuries needed to induce a defined thrombus was used. All low-molecular-weight heparins (preparation B, Braun; BR-Z-0601, Braun; CY 216, Choay; Fragmin, Kabi; low molecular heparin, Sandoz and Org 10172, Organon) or unfractionated heparin (Liquemin®; Hoffmann-La Roche) showed a significant and dose-dependent antithrombotic effect after subcutaneous injection, if venules had been damaged. The effect lasted for 48 h, partly for over 48 h. If thrombus formation was studied after intravenous injection into arterioles as well as into venules 8 h after injection, no antithrombotic effect could be demonstrated under the influence of CY 216 or unfractionated heparin.
Anti-IIa and Anti-Xa Plasma Activities after Subcutaneous Low-Dose Application of Low-Molecular-Weight Heparins to Rabbits
Authors: Harbauer G. , Kettenring P.
Published: April 2009

Low-molecular-weight heparin (LMWH) derivatives differ among one another and from unfractioned heparin (UFH) in their half-life as well as in their mode of action. Our aim was to find out, whether the plasma activity levels and their time course after subcutaneous low-dose application of LMWH or UFH in the experimental rabbit are comparable to those in humans. Fairly reasonable standard curves for each LMWH preparation were obtained by using geometrical dilution series of spiked rabbit pool plasma and by applying the methods of Bartl et al. [1] (anti-IIA) and Holmer et al. [2] (anti-Xa). The latter method was slightly modified in order to achieve discernable photometric absorptions for activity levels <0.05 U/ml. Rabbits under intravenous general anesthesia received an anterior neck incision. The right external jugular vein was dissected free. A catheter was inserted, advanced into the upper caval vein and kept patent by continuous infusion of 10 ml/h of normal saline. Blood samples of 4 ml were collected in syringes containing 1 ml sodium citrate, before and 1, 2, 4 and 8 h after subcutaneous injection of a LMWH derivative or UFH. The samples were centrifuged and frozen to –30°C. For the estimation of heparin-like anti-IIa and anti-Xa activities the samples were thawed and treated in the same manner as the samples from which the standard curves had been derived. 6 different LMWH preparations and 1 UFH preparation were tested, each in 6 rabbits. We obtained rather reasonable absorption values, indicating increases in heparin-like activities after injection followed by gradual decreases with a maximum 2–4 h after injection. But there were great differences in the individual 0 values of the samples taken before the injection. In many cases there were relative low absorption values (as if there existed some spontaneous heparin-like activity), but in some cases there were very high absorption values (as if there was an excess of thrombin or active factor Xa). The main problem seems to be to obtain reliable measurement results from very low LMWH or UFH plasma levels.
Primary and Secondary Long-Term Prophylaxis of Thromboembolism in Outpatients with the Low-Molecular-Weight Heparin Kabi 2165
Authors: Harenberg J. , Leber G. , Raedsch R. , Zimmermann R. , Schwarz F. , Kübler W.
Published: April 2009

Bleeding episodes and other side effects may complicate the treatment with oral anticoagulants. We report on the results of 66 patients who were treated with a low molecular weight heparin fraction for up to 19 months. The data of the study demonstrate the effective long-term anticoagulation with low-molecular-weight heparin and the reduced incidence of hemorrhages compared with conventional anticoagulants. Thus, low-molecular-weight heparin may be effectively and safely used for long-term anticoagulation in patients with bleeding problems on conventional anticoagulants.
Signaling Pathways Controlling Second Heart Field Development
Authors: Rochais Francesca , Mesbah Karim , Kelly Robert G.
Published: April 2009

Insight into the mechanisms underlying congenital heart defects and the use of stem cells for cardiac repair are major research goals in cardiovascular biology. In the early embryo, progenitor cells in pharyngeal mesoderm contribute to the rapid growth of the heart tube during looping morphogenesis. These progenitor cells constitute the second heart field (SHF) and were first identified in 2001. Direct or indirect perturbation of SHF addition to the heart results in congenital heart defects, including arterial pole alignment defects. Over the last 3 years, a number of studies have identified key intercellular signaling pathways that control the proliferation and deployment of SHF progenitor cells. Here, we review data concerning Wnt, fibroblast growth factor, bone morphogenetic protein, Hedgehog, and retinoic acid signaling that have begun to identify the ligand sources and responding cell types controlling SHF development. These studies have revealed the importance of signals from pharyngeal mesoderm itself, as well as critical inputs from adjacent pharyngeal epithelia and neural crest cells. Proliferation is emerging as a central checkpoint in the regulation of SHF development. Together, these studies contribute to defining the niche of cardiac progenitor cells in the early embryo, and we discuss the implications of these findings for the regulation of resident stem cell populations in the fetal and postnatal heart. Characterization of signals that maintain, expand, and regulate the differentiation of cardiac progenitor cells is essential for understanding both the etiology of congenital heart defects and the biomedical application of stem cell populations for cardiac repair.
Increasing Memory Capacity and Reducing Spurious States in Neural Networks by Introducing Coherent and Collective Firing
Authors: Koh Yang Wei , Takatsuka Kazuo
Published: April 2009

It is well known that higher-order Hopfield nets called multispin models can increase memory capacity to some extent by extending the direct product of spin states to more than second order. However, a group of neurons can then respond degenerately to different loaded patterns, resulting in many spurious states due to cross-talk effects. We present an idea to increase the number of attracting basins for patterns while suppressing the associated spurious states, by introducing coherent and collective firing in multispin groups. We numerically implement the method and test the number, stability, and basin size of the attractors thus created. Increasing the size of a group of coherent excitation suppresses spurious states, stabilizes loaded patterns, and dramatically increases the number of pattern attractors.
The Continuous Spectrum in Baroclinic Models with Uniform Potential Vorticity Gradient and Ekman Damping
Authors: de Vries Hylke
Published: April 2009

Analytic solutions of the continuous spectrum are obtained for quasigeostrophic models in which the basic-state meridional potential vorticity (PV) gradient is uniform but nonzero. The modes that form the continuous spectrum—continuum modes—are baroclinically neutral, singular solutions of the linear dynamical equations, which have an interior critical level. Although most inviscid shear flows support continuous spectra, previous studies have largely been restricted to models in which the interior PV gradient is zero. In that situation, continuum modes are formed by a superposition of boundary potential temperature anomalies and an interior PV δ function at the critical level. Here it is shown how a nonzero interior PV gradient and Ekman damping nontrivially affect the vertical structure of continuum modes. A consideration of the perturbation PV further rationalizes their vertical structure.
Lightning Flash Rates as an Indicator of Tropical Cyclone Genesis in the Eastern North Pacific
Authors: Leary Lesley A. , Ritchie Elizabeth A.
Published: April 2009

Lightning flashes in convective tropical clusters of the eastern North Pacific Ocean are detected by the Long-Range Lightning Detection Network and are analyzed for temporal patterns in electrical activity. The rates of lightning flash discharge in the 2006 season are analyzed for both tropical cyclones and nondeveloping cloud clusters to 1) determine if there is a difference in the convective activity of these two populations and 2) find a level of electrical activity that constitutes development in a particular system. Convective activity is associated with tropical cyclogenesis and thus we use the rate of electrical discharge as a proxy for convection associated with the likelihood of organization of individual cloud clusters into a tropical depression strength system. On the basis of the rates of lightning flashes in the cloud clusters, four levels of development are defined, ranging from non- and partially developing to fully developing cloud clusters. The levels of development are further supported by the analysis of other remotely sensed observations, such as surface scatterometer winds, that allow for the description of the mesoscale and large-scale circulation patterns in which the cloud clusters are embedded. It is found that lightning flash rates distinguish those cloud clusters that do not fully develop into tropical depressions from those that do. Receiver operating characteristic curves for these groupings are calculated, and a level of flash rate can be chosen that gives a probability of detection of 67% for a false-alarm rate of 24%.
Mechanism‐Based Enterohepatic Circulation Model of Mycophenolic Acid and Its Glucuronide Metabolite: Assessment of Impact of Cyclosporine Dose in Asian Renal Transplant Patients
Authors: Yau Wai‐Ping , Vathsala Anantharaman , Lou Huei‐Xin , Zhou Shufeng , Chan Eli
Published: April 2009

Mycophenolic acid (MPA) is mainly metabolized to MPA‐glucuronide (MPAG), which may be reconverted to MPA following enterohepatic circulation (EHC). A physiologically realistic EHC model was proposed to estimate and assess the impact of cyclosporine (CsA) dose on the extent of EHC of MPA and MPAG. After the first oral dose of mycophenolate mofetil (MMF), the MPA and MPAG plasma concentration‐time data of 14 adult renal transplant patients (12 receiving concomitant CsA and prednisolone and 2 receiving only concomitant prednisolone without CsA) were analyzed by individual pharmacokinetic modeling using a proposed 5‐compartment drug and metabolite EHC model with a time‐varying gallbladder emptying process. Simulations were performed to assess the influence of the time of bile release after dosing (Tbile) and the gallbladder emptying interval (τgall) on the EHC process. The extent of EHC for both MPA and MPAG tended to be lower in the group receiving CsA coadministration and decreased with increasing total body weight—adjusted CsA dose. Simulations revealed that Tbile and τgall influenced the time of occurrence and maximum concentration of the second peak, as well as the extent of EHC, for MPA and MPAG.
Predictors of Prenatal Multivitamin Adherence in Pregnant Women
Authors: Nguyen Patricia , Thomas Martin , Koren Gideon
Published: April 2009

There is no study available that has investigated determinants of prenatal multivitamin adherence among pregnant women, based on gastrointestinal (GI) adverse events. The objective of this study was to identify determinants predicting adherence to prenatal multivitamins in pregnant women who were randomized to take 2 different supplements. The authors recruited and interviewed 70 women on the importance of various factors that may have affected adherence to previous and assigned multivitamins. The different factors included GI symptoms and swallowing difficulty. The authors used a 5‐point scale to measure degree of importance. The highest scoring factors for not taking or discontinuing any previous multivitamins were fear of or experience of nausea, vomiting, and gagging. For women who never took the assigned prenatal multivitamins, the highest scoring factors contributing to that decision were fear of nausea, fear of vomiting, and health care provider advice. For women who started taking the assigned supplements, the most important factors affecting adherence were dosing regimen, health care provider advice, and mode of product distribution. Adherence to assigned prenatal multivitamins significantly correlated only with the importance of constipation in deciding to discontinue any previous multivitamins. It is concluded that predictors of adherence to recommended prenatal multivitamins during pregnancy are rooted in women's prior experiences with multivitamin use.