bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunochemical Characterization of Crosslinked Derivatives Isolated from Alpha Chain Oligomers Formed During Early Stages of Fibrin Crosslinking
Authors: Sobel Joan H , Thibodeau Christiane A , Ann Gawinowicz Kolks Mary , Canfield Robert E
Published: June 2018

Early crosslinked α chain oligomers (EαXL) that formed within ½ h of in vitro clot formation were isolated from preparations of reduced, carboxymethylated fibrin by gel filtration on Sepharose CL-4B. Cyanogen bromide (CNBr) digestion of EaXL released a mixture of fragments which could be partially separated by Sephadex G-150 chromatography. Crosslinked ahd noncrosslinked forms of the Aα chain peptides, CNBr VIII (Aα #241-476) and CNBr X (Aα #518-584) were identified in the column effluent both by radioimmunoassay (RIA) and by immunoblotting using polyclonal antisera (anti-CNBr VIII, anti-CNBr X) and monoclonal antibodies (F-103, binds to Aα #259-276; F-102, binds to Aα #540-554), respectively. Immunoaffinity chromatography of the crosslinked material, on F-103, followed by F-102 Sepharose, resulted in the separation of two types of fragments, each of which contained an early a chain crosslink. One of these (35-37K) exhibited coincident CNBr VIII and CNBr X immunoreactivities, while the other (54-59K) exhibited only CNBr VIII immunoreactivity, based on immunoblotting and RIA findings. NH2-terminal sequencing and cyanoethylation data provided biochemical evidence for the occurrence of covalent CNBr VIII-X as well as covalent CNBr VIII-VIII interactions during early a chain crosslinking. These findings indicate, for the first time, that both glutamine acceptor and lysine donor activities may be localized within CNBr VIII. This information should facilitate the chemical identification of a chain residues that partner during factor XIIIa-catalyzed crosslinking and thus enable development of reagents for the generation of fibrin-specific antibodies.
Glucose Inhibits Prostacyclin Production by Cultured Aortic Endothelial Cells
Authors: Ono Hiroshi , Umeda Fumio , Inoguchi Toyoshi , Ibayashi Hiroshi
Published: June 2018

A reduction in production of prostacyclin (PGI2) by the cells in the vascular wall may play a role in the pathogenesis of atherosclerosis in diabetic patients. The present study was undertaken to evaluate the effect of glucose on PGI2 production by endothelial cells in vitro. It was shown that PGI2 production by cultured bovine aortic endothelial cells was significantly reduced in the presence of a high concentration of glucose (300 mg/dl) compared with physiological concentrations of glucose (100 mg/ dl). In contrast, no reduction in PGI2 production was observed in cells cultured with equimolar mannitol, suggesting that glucose itself, rather than the effect of osmolality, inhibited PGI2 production by cultured endothelial cells.

In addition, a high concentration of glucose also inhibited the proliferation of cultured endothelial cells.
Conditions Affecting the Responses of Human Platelets to Epinephrine
Authors: Keraly Chantal Lalau , Kinlough-Rathbone Raelene L , Packham Marian A , Suzuki Hidenori , Mustard J Fraser
Published: June 2018

Conditions affecting the responses of human platelets to epinephrine were examined. In platelet-rich plasma prepared from blood anticoagulated with hirudin or PPACK (D-pheny- lalanyl-L-prolyl-L-arginine chloromethyl ketone), epinephrine did not cause shape change or aggregation. In a Tyrode-albumin- apyrase solution containing a concentration of Ca2+ in the physiological range, and fibrinogen, epinephrine in concentrations as high as 40 μM did not induce platelet shape change, caused either no primary aggregation or very slight primary aggregation, and did not induce thromboxane formation, release of dense granule contents, or secondary aggregation. In contrast, in citrated platelet-rich plasma, epinephrine induced two phases of aggregation. This is not attributable to the generation of traces of thrombin since the same effects were evident when blood was taken into a combined citrate-hirudin anticoagulant or a combined citrate-PPACK anticoagulant. In a modified Tyrode-albu- min-apyrase solution containing approximately 20 μM Ca2+, 1 mM Mg2+, and fibrinogen, epinephrine induced extensive aggregation after a lag phase, but no primary phase was evident; thromboxane formation and release of dense granule contents accompanied the aggregation response. These responses were also observed when PPACK was included with the acid-citrate- dextrose anticoagulant, and in the washing and resuspending fluids. In the presence of aspirin or the thromboxane receptor blocker BM 13.177 a few small aggregates were detected by particle counting and by scanning electron microscopy; with the latter inhibitor, the platelets in the aggregates retained their disc shape; secondary aggregation and the responses associated with it did not occur. Thus thromboxane A2 formation is not necessary for the formation of these small aggregates, but is required for extensive aggregation and release. As with other weak agonists, the close platelet-to-platelet contact in the low Ca2+ medium appears to be necessary for full secondary aggregation. Omission of fibrinogen from the low Ca2+ medium prevented both primary and secondary aggregation in response to epinephrine. An antibody (10E5) to the glycoprotein Ilb/IIIa complex was completely inhibitory in the presence of fibrinogen. Thus the response of human platelets to epinephrine is influenced by the concentration of Ca2+ and the presence of fibrinogen in the medium in which they are suspended.
Relative Sensitivity of Different Tests in the Detection of Low Titer Lupus Anticoagulants
Authors: Lesperance B , David M , Rauch J , Infante-Rivard C , Rivard G E
Published: June 2018

Lupus anticoagulants (LA) and anticardiolipin antibodies have been strongly associated with recurrent abortion and fetal death. Because steroids have been reported to improve the fetal outcome of LA associated pregnancies, presumably by decreasing the levels of LA, it becomes desirable to have a simple and reliable test to monitor the levels of the putative antibody. To this effect, we assessed the capacity of the following coagulation tests to detect the presence of LA in serial dilutions of patient plasma with pooled normal plasma: kaolin clotting time (KCT), tissue thromboplastin inhibition test (TTIT), dilute Russell Viper venom time (DRVVT) and activated partial thromboplastin time with standard and high concentrations of phospholipids (SC and HCAPTT). All samples were also evaluated for the presence of anticardiolipin antibodies with an ELISA. The KCT was able to detect LA at a much greater dilution in normal plasma than any of the other clotting assays. The ELISA was comparable to KCT in its ability to detect high dilutions of LA.
Von Willebrand Factor and Mitral Valve Prolapse
Authors: Froom P , Margulis T , Grenadier E , Palant A , David M , Aghai E
Published: June 2018

The levels of von Willebrand factor (vWF: Ag) were measured in 27 patients with mitral valve prolapse (MVP) and compared to 27 age matched controls. Decreased levels of vWF:Ag (<80%) were found in 59% (16/27) of those with MVP compared to only 7% (2/27) of the controls (p <0.001). Mean vWF: Ag levels were also significantly lower in those with MVP (68 ± 30% versus 100 ± 23%, p <0.001). In those with MVP and congestive heart failure secondary to ruptured chordae tendineae, however, the mean level of vWF:Ag was not significantly different from control values (95 ± 32). There was an increased incidence of recurrent nose bleeds in those with MVP and low levels of vWF: Ag. We conclude that there is a relationship between MVP and low levels of vWF:Ag which may explain the increased incidence of epistaxis in such patients. Increased release of vWF: Ag in those with MVP and concomitant congestive heart failure may account for the normal levels found in this subgroup.
Plasminogen Activators in the Intestine of Patients with Inflammatory Bowel Disease
Authors: de Bruin P A F , Crama-Bohbouth G , Verspaget H W , Verheijen J H , Dooijewaard G , Weterman I T , Lamers C B H W
Published: June 2018

Plasminogen activators were determined in intestinal tissue, obtained after surgery from patients with Crohn’s disease and ulcerative colitis, and compared with normal intestinal tissue from colorectal cancer patients.

The activity and quantity of tissue-plasminogen activator (t-PA) was found to decrease with the severity of inflammation in the patients with inflammatory bowel disease. Urokinase (u-PA) activity, however, was not changed compared with controls or in relation with severity of inflammation. In contrast, the level of u-PA antigen was found to be increased significantly in the inflammatory bowel disease tissues and was also related with severity of inflammation. The difference between u-PA activity and antigen in inflammatory bowel disease tissue could be attributed to an increase in inactive pro-u-PA and u-PA-inhibitor complexes.

This increase in u-PA and the concomitant decrease in t-PA, are similar to those found in premalignant colonic adenomas, and might be related to the known increased cancer risk in inflammatory bowel disease.
The Effect of Enzymatic Removal of Sialic Acids on the Functional Properties of Protein C
Authors: Hau Lena , Salem Hatem H
Published: June 2018

The effect of enzymatic removal of sialic acid residues on the functional properties of human protein C was examined. The rates of activation of native and asialo protein C were identical using either the thrombin thrombomodulin complex or the snake venom activator, protac. Desialylated activated protein C (APC) was, two-three-fold more active than native protein C, both as an anticoagulant and in its ability to hydrolyze chromogenic substrates. The potentiating effect of the desialylation was confirmed by initially fully activating protein C followed by the desialylation process. In these studies, a two-three-fold enhancement in the activity of the protein was observed which paralleled the extent of the desialylation. The activity of asialo-protein C was completely abolished by monoclonal and polyclonal antiprotein C antibodies, confirming that the effect was mediated by APC. Our studies suggest that the sialic acid component of protein C is not essential for the expression of APC activity but may act to modulate the function of the protein.
The Effect of Human Recombinant Tissue-Type Plasminogen Activator on Clinical and Laboratory Parameters of Hemostasis and Systemic Plasminogen Activation in the Dog and the Rat
Authors: Bloom John C , Sellers Teresa S , Gries Gary C , Wheeldon Eric B , O'Brien Susan R , Lewis Hugh B
Published: June 2018

The effect of human recombinant tissue-type plasminogen activator (rt-PA) on parameters of hemostasis and systemic plasminogen activation was studied in the dog and rat. Effects on screening coagulation times, fibrinogen concentration, fibrin/fibrinogen degradation products, and plasminogen and α2-anti- plasmin (α2-AP) activities in plasma were examined following single bolus injections of 0.5-5.0 mg/kg, single and repeated 3 hr infusions of 0.75-7.5 mg/kg and 24 hr infusions of 6.0 and 30.0 mg/kg administered intravenously to dogs. Rats receiving single or 14 daily injections of 5.0-30.0 mg/kg i.v. were similarly monitored. Systemic fibrinogenolysis (>50% decrease in fibrinogen, plasminogen or α2-AP values) was observed in dogs receiving ≥1.0 mg/kg as a bolus, ≥3.75 mg/kg (20.8 μg or 1.19 × 104 IU kg−1min−1) as a 3 hr infusion and >6 mg/kg (4.2 μg or 2.42 × 103IU kg−1min−1) as a 24 hr infusion; and in rats treated with bolus injections of 30 mg/kg rt-PA. Clinical and laboratory indications of impaired hemostasis and bleeding (anemia, prolonged coagulation times and post-mortem evidence of hemorrhage) were associated with these effects, which together were dose-dependent and influenced by the rate of infusion. The incidence of major hemorrhage was variable and limited to animals receiving prolonged (24 hr) or repeated infusions.
Conditions Influencing the Interaction of Asialo von Willebrand Factor with Human Platelets – The Effects of External Ionized Calcium Concentration and the Role of Arachidonate Pathway
Authors: Cattaneo Marco , Mustard J Fraser , Canciani Maria T , Richardson Mary , Federici Augusto B , Mannucci Pier Mannuccio
Published: June 2018

We have studied the interaction of ASvWf with human platelets in PRP and in suspensions of washed platelets containing either physiological or low external ionized calcium concentration [Ca2+]0. In hirudin-PRP or in washed platelets in 1.5-2 mM CaCl2, ASvWf up to 50 μg/ml does not induce platelet aggregation or the release reaction. When [Ca2+]c is decreased by addition of citrate to hirudin-PRP or when no CaCl2 is added to washed platelet suspensions, ASvWf does induce platelet aggregation and the release reaction. In low [Ca2+]0, ASvWf interacts with platelet GPIb to cause primary aggregation of disc-shaped platelets to each other through GPIIb/IIIa, with or without added fibrinogen. This primary platelet aggregation leads to thromboxane A2 formation and secondary aggregation and the release reaction. With [Ca2+]0 in the physiological range, there is less ASvWf interaction with GPIb, no primary platelet aggregation and no thromboxane A2 formation. The ASvWf-platelet interaction at physiological [Ca2+]0, however, enhances the platelet response to collagen or epinephrine.
Fibrinolysis Resistant Fibrin Deposits in Lymph Nodes with Hodgkin's Disease
Authors: Ádány Róza , Szegedi Andrea , Ablin Richard J , Muszbek László
Published: June 2018

Extravasal fibrin deposition is frequently observed within and around tumorous tissues and has been implicated in various aspects of tumor growth. However, no adequate information has been available on the mechanism how intratumoral interstitial fibrin deposits escape a prompt elimination by the fibrinolytic system. In this study we provide immunomorphological evidence showing that fibrin deposits in lymph nodes with Hodgkin's disease are stabilized and made resistant to fibrinolysis by factor XIII (FXIII) of blood coagulation. By double immuno- fluorescent labelling systems fibrin deposits were simultaneously stained for α2-antiplasmin (α2-AP), the main physiological inhibitor of fibrinolysis and in a number of nodular areas they were also labelled for plasmin (ogen). The detection of α2-antiplasmin-plasmin complex-neoantigen (α2-AP-P-Neo) revealed that α2-AP reacted with plasmin, i.e., α2-AP covalently linked to fibrin indeed inhibited intratumoral fibrinolysis. In addition to fibrin deposits FXIII was also found in cellular elements characterized earlier as tumor associated macrophages. These cells were attached to fibrin strands suggesting that they are involved in the intratumoral fibrin formation and might be a source of fibrin stabilizing factor in the tumor stroma.
Induction of Fibrinolysis by Polyanions in Human Plasma
Authors: Klauser Rainer J
Published: June 2018

The fibrinolytic potency of several polyanions was comparatively investigated. Fibrinolytic activity was measured in a whole plasma assay using H-D-Val-Leu-Lys-pNA (S-2251) as chromogenic substrate and by a fibrin plate assay using plasminogen rich fibrin plates.

In the chromogenic substrate assay potent fibrinolytic polyanions comprised dextran sulfate, GAGPS, pentosan polysulfate, polyanethol sulfate, 1-carrageenan and i-carrageenan. Chon- droitin sulfates A, B, ‘C, keratan sulfate, ribonucleic acid, k-carrageenan and heparin were weakly fibrinolytic. Hyaluronic acid and lipopolysaccharide from E. coli were inactive.

Similar results were obtained when fibrinolytic activity was measured by a fibrin plate assay. All polyanions except lipopolysaccharide produced lysis zones.

Induction of fibrinolytic activity in human plasma was shown to be at least partially dependent on Hageman factor. In factor XII deficient plasma no fibrinolysis was induced by any of the polyanions when measured in the fibrin plate assay.

In the. chromogenic substrate assay corn Hageman factor inhibitor (CHFI) inhibited the activation of S-2251 cleaving enzyme by GAGPS, pentosan poly sulfate, polyanethol sulfate, heparin, and ribonucleic acid near completely. The activation by dextran sulfate was inhibited by 45%.

Heparin, pentosan polysulfate and GAGPS, three poly anions of therapeutic interest were separately compared. In both assays GAGPS proved the most potent activator, while pentosan poly sulfate exhibited 83% and 44% and heparin 32% and 14% of GAGPS fibrinolytic activity in the chromogenic substrate test and the fibrin plate assay, respectively.
Monoclonal Antibodies Against the Heparin- Dependent Protein C Inhibitor Suitable for Inhibitor Purification and Assay of Inhibitor Complexes
Authors: Laurell Martin , Carlson Timothy H , Stenflo Johan
Published: June 2018

summary

Two different monoclonal antibodies against the heparin- dependent inhibitor of human activated protein C were produced, using cleaved modified inhibitor for immunization and partially purified inhibitor for screening of the hybridomas, One of the antibodies recognized free and complexed forms of the inhibitor in immunoblotting experiments. The other antibody was used to develop an assay for A PC -PCI inhibitor complexes. Using the assay the formation of complexes was studied in plasma, both in the presence and absence of heparin. The rate of complex formation was similar to that reported previously for the loss of activated protein C amidolytic activity in plasma. The same antibody was also immobilized on Sepharose and used to purify the inhibitor from fresh human plasma. The purified material appeared as two narrowly spaced bands with Mr about 57,000 in SDS-PAGE. The average yield from 1 liter of fresh plasma was 1 mg of inhibitor, The purified inhibitor formed SDS stable complexes with activated protein G and urokinase that could be identified in immunoblots using specific antibodies.
Dysfunctional Activated Protein C (PC Cádiz) in a Patient with Thrombotic Disease
Authors: Sala N , Borrell M , Bauer K A , Viganò-D’Angelo S , Fontcuberta J , Félez J , Rutllant M L
Published: June 2018

The partial characterization of a dysfunctional protein C (PC), provisionally named “PC Cádiz”, in a 45-year-old male patient suffering from recurrent venous thrombosis is described. The only defect found in laboratory assays for haemostasis and hepatic function was a half normal level of both amidolytic and anticoagulant protein C activity, measured by different functional assays that use thrombin-thrombomodulin complex and a snake venom to activate protein C. Protein C antigen was always found to be within normal levels. Two young daughters of the propositus were found to have the same defect. Double-crossed immunoelectrophoresis, performed in the presence and absence of Ca2+ in the first dimension, showed no clear differences between patient and control PC. PC adsorption to barium salts was also found to be normal. Measurement of the PC activation peptide in the barium citrate eluates after PC activation showed no significant differences between patient and 10 normal controls, the concentration of this peptide being very similar to that of PC zymogen in the same eluates before PC activation. These results indicate that this abnormal PC is able to be normally activated by thrombin-thrombomodulin complex but does not exhibit serine protease activity, probably due to a defect in the PC molecule near the active site center.
Production of the Generalized Shwartzman Reaction by Activated Hageman Factor and α-Adrenergic Stimulation
Authors: McKay D.G , Latour J.-G , Lopez Anatalia M.
Published: June 2018

Infusion of activated purified Hageman factor and norepinephrine into pregnant rats produces renal glomerular capillary thrombosis identical to the generalized Shwartzman reaction. Activated Hageman factor alone, norepinephrine alone, and inosithin (a substitute for platelet phospholipid) alone, in addition to the combination of inosithin and norepinephrine were incapable of causing the reaction. These studies confirm the evidence that four basic components of the reaction are 1. activation of Hageman factor, 2. platelet phospholipid, 3. ‘‘fibrinolysin inhibition’’, and 4. stimulation of α-adrenergic receptor sites.
Antithrombin
Authors: Dombrose Frederick A. , Seegers Walter H. , Sedensky James A.
Published: June 2018

An evaluation of the mode of action of antithrombin in the temporary inhibition of purified 3.7 S bovine thrombin was made according to traditional enzyme inhibition theory. Using enzyme clotting activity and concentration of active sites synonymously, it was observed that the binding of antithrombin to thrombin followed a second order reaction that could be distinguished into an essentially irreversible phase and a slower, potentially reversible phase. The level of steady state enzyme inhibition depended upon the ratio of the initial concentrations of enzyme to antithrombin. In addition, there occurred a rapid enhancement of enzyme esterolytic activity during the concomitant loss in clotting activity. This enhancement was also observed for acetylated thrombin which had no proteolytic activity. Under high concentrations of antithrombin, this enhancement subsequently deteriorated. A working hypothesis, including equations, for a mutual depletion system is presented to account for the known parameters of enzyme inhibition by antithrombin. We compared the neutralization of thrombin C with autoprothrombin C and found that each enzyme responds to antithrombin according to similar kinetic relationships.
Quantitative Effects of the Reaction between Factor VIII and Factor VIII Inhibitors
Authors: McMillan C. W , Elston R. C
Published: June 2018

To study the effects of factor VIII and factor VIII inhibitor on each other an assay was developed in which inhibitor activity could be directly related to units of factor VIII. Inhibitor activity in units per ml is defined as the number of factor VIII units reduced to 0.01 factor VIII unit by 1 ml inhibitor plasma after incubation for 1 h at 37° C. Whereas factor VIII was destroyed by inhibitor in accord with a double-logarithmic relation between initial and 1-h residual factor VIII activities, final inhibitor activity was found to be inversely proportional to the ratio of initial concentrations of factor VIII to inhibitor. The latter process resembles “dilution”, rather than direct neutralization, of inhibitor by factor VIII. These effects were observed both in the system for inhibitor assay and in more concentrated mixtures of factor VIII and inhibitor sources in vitro. Results of infusion of factor VIII into a subject with classic hemophilia and an acquired inhibitor suggested that in vivo and in vitro effects of factor VIII and inhibitor activities on each other are comparable, if not identical.
Studies on Liver Factors which Exert an Inhibitory Effect on Platelet Aggregation
Authors: Rogowski W , GaŁasiński W , Bańkowski E , Rzeczycki W
Published: June 2018

The inactivating effect of rabbit liver homogenates on platelet aggregation was investigated.

The active substances were found in a nonprotein fraction of the liver homogenates. They were separated and identified as nucleotides and nucleosides. It was found that the platelet aggregation inhibiting substances obtained from the liver, inactivated the platelet aggregating factors, such as ADP, thrombin and collagen. Nucleosides and nucleotides were chromatographically separated from the liver homogenates, and their effect examined on the platelet aggregating factors. The probable mechanism of their inactivation and their pathophysiological significance are discussed.
The Action of an Aniline Derivative (AN 162) on Blood Coagulation and on Platelets
Authors: Deutsch E , Lechner K , Moser K , Stockinger L
Published: June 2018

1. The aniline derivative AN 162, Donau Pharmazie, Linz, Austria, has a dual action on the blood coagulation: an anticoagulant and an coagulation enhancing effect.

2. The anticoagulant action may only be demonstrated with high concentrations (over 1 X 10”3 M related to plasma) preferentially in PPP. It is partially caused by an inhibition of the endogenous way of generation of the prothrombin converting principle. In addition it is suggested that it interferes with the fibrinogen-fibrin reaction in a manner not yet understood.

3. The coagulant action is caused by a greater availability of platelet constituents at low concentrations of AN 162 (over 1 × 10-4 M) and by the induction of a release reaction at higher concentrations. The platelet factors 3 and 4, serotonin, adenine, and acid phosphatase are released.

4. AN 162 inhibits platelet aggregation. This inhibition can be demonstrated by the PAT of Breddin and in the stirred aggregation test of Born. It is more effective to inhibit the collagen-induced and the second phase of the adrenaline-induced aggregation than the ADP induced one. The platelet retention (test of Hellem) is also reduced.

5. The action of AN 162 on the platelets is caused by a damage of the platelet membrane which becomes permeabel for both, soluble platelet constitutents and granula.

6. AN 162 interferes with the energy metabolism of the platelets. It causes a loss of ATP, and inhibits the key-enzymes of glycolysis, citric acid cycle, fatty acid oxydation and glutathione reduction.

7. AN 162 inhibits the growth of fibroblasts without influence on mitosis.
Purification and Properties of the Thrombin-Like Principle of Agkistrodon acutus Venom and Its Comparison with Bovine Thrombin
Authors: Ouyang Chaoho , Hong Jau-Shyong , Teng Che-Ming
Published: June 2018

By means of DEAE-Sephadex column chromatography, Agkistrodon acutus venom was separated into 12 fractions. The thrombin-like activity was concentrated in Fr.10. This fraction was rechromatographed on Sephadex G-200. A single band was found on microzone electrophoresis at pH 7.4. A single boundary with S20, w of 3.82 S, which was almost symmetrical, was observed by ultracentrifugation. The estimated molecular weight is 33,500. The chemical analysis shows that the thrombin-like principle of the venom is a glycoprotein. The specific activity is 13 times higher than that of the crude venom. The optimal pH value of the thrombin-like principle (pH 7.5) of the venom is almost identical with that of the bovine thrombin (pH 7.2). The thrombinlike principle of the venom is not affected by heparin, while the clotting activity of the bovine thrombin is inhibited by heparin. The thrombin-like principle of the venom is much more heat stable than the bovine thrombin.

No clot retraction was found with the thrombin-like principle of the venom, while the marked clot retraction occurred after plasma was coagulated with thrombin.

Thrombin can activate factor XIII (Fibrin stabilizing factor), while the thrombinlike principle can not.
The Differentiation of Acid Phosphatases of Human Blood Platelets
Authors: Kaulen H. D , Gross R
Published: June 2018

The Acid Phosphatase was tested in human platelets and in the rat liver mitochondrial-lysosomal fraction with p-nitrophenylphosphate and β-glycerophosphate as substrates. In the platelets the following differences were found between the hydrolysis of these two substrates, whereas in rat liver no such differences were observed. 1. The relative rates of hydrolysis and the pH optima for both substrates are different (pH 4.6 for the β-glycerophosphatase, pH 6.0 for the p-nitrophenylphosphatase in the platelets). 2. The p-nitrophenylphosphatase of the platelets is inhibited by p-chlormercuribenzoate and N-ethylmaleimide, but not by fluoride or L + tartrate, whereas the contrary is true for the platelet β-glycerophosphatase and the rat liver activities. 3. The platelet p-nitrophenylphosphatase is rapidly inactivated by preincubation at 40-45° C for 15 min, the other phosphatases are much more heat-resistant. 4. Sucrose density gradient centrifugation of platelet homgenates showed a separation of the two platelet phosphatase activities, the p-nitrophenylphosphatase with its maximum at lower densities than the β-glycerophosphatase.

It is concluded that in human platelets there are at least two different Acid Phosphatases. The β-glycerophosphatase probably represents the lysosomal (as compared to the rat liver enzyme) phosphatase whereas the p-nitrophenylphosphatase of the platelets is a different enzyme whose subcellular localization and functions are as yet unknown.
The Human Blood Platelets as a Molecular Mosaic Its Role in Aggregation and Thrombus Formation
Authors: Mehrishi J. N
Published: June 2018

On the surface of human blood platelets various types of groups are present - sulphydryl groups, positively charged amino groups and at least three types of anionogenic groups. The numbers of these groups on a per cell basis have been calculated and then* relative contributions to the net charge determined. Two arrangements for the distribution of the groups in the cell periphery have been proposed. Such studies provide a molecular basis for many reactions taking place at the cell surface. The role of these groups in platelet aggregation and thrombus formation is discussed
Effects of Anti-Adhesive Agents on the Ultrastructure of Rabbit Blood Platelets in Vitro
Authors: Dougherty W. J , Bicher H. I
Published: June 2018

The in vitro effects of two anti-adhesive agents, designated as substances “86” and BLR-743, on the ultrastructure of rabbit blood platelets were examined. When compared with control platelet preparations, it was found that these agents, over a 10 min period, induced platelets to become spiny spheres. Vacuoles of the surface connected system inside platelets tended to enspherulate, also. No change in structure or location of form-maintaining structures such as microtubules were observed in treated platelets. Neither were changes observed in the structure or location of mitochondria. While the distribution within platelets of α-granules and vacuoles containing 5-hydroxytryptamine granules seemed to be little affected by treatement of platelets with these agents, 5-hydroxytryptamine granules were reduced in number and α-granules expressed variable degrees of electron density suggesting variable degrees of extraction of materials from these granules. It is concluded on the basis of the morphologic changes in platelets observed that the anti-adhesive agents have a primary action on the plasma membrane and other membrane bound structures of blood platelets.
Platelet Count and Platelet Stickiness in Rats
Authors: Grüner O. P. N , Endresen G. K. M
Published: June 2018

In rat, a transected tail vessel proved an adequate source of blood for platelet enumeration. When suspensions of rat blood in ammonium oxalate were rotated for 1 h a significant loss of platelets was observed. This platelet reduction rate (PRR), calculated as per cent of the pre-rotation count, showed individual constancy and inter-individual variance.
The Effect of Fibrinolysis Inhibitors on the Ellagic Acid Activation of Hageman Factor in the Dog
Authors: Girolami A , Fioretti D , Cella G , Pedrazzoli G , Bernardi R
Published: June 2018

The administration of 10 ml/kg b.w. of a 10−4 M ellagic acid solution to dogs primed with saline (control group) caused a marked shortening of the silicone clotting time and a mild shortening of the glass clotting time whereas no changes in the euglobulin lysis time were noted. The administration of the compound to dogs primed with Trasylol (10,000 K.I.U./kg b.w.) failed to cause any change in the clotting times but caused instead a sharp inhibition of fibrinolysis. The administration of ellagic acid to dogs primed with EACA (0.3 g/kg b.w.) caused a shortening of the silicone and glass clotting times similar to that observed in the control group whereas fibrinolysis was not significantly inhibited. These data indicate that Trasylol inhibits Hageman factor activation by ellagic acid whereas EACA has no effect.
Impaired Fibrinolysis in Sickle Cell Disease
Authors: Green D , Kwaan H. C , Ruiz G
Published: June 2018

Coagulation studies were performed in 52 patients with sickle cell disease during asymptomatic periods and during episodes of crisis and infection. Platelet counts averaged 473,000, 469,000, and 461,000 per mm3 in these 3 groups, and factor VIII concentrations were elevated in all. Fibrinogen was increased to the same extent in both sickle cell and non-sickle cell patients with infection. Fibrinolytic activity, as measured by euglobulin lysis times and zones of lysis on fibrin plates, was markedly reduced during periods of infection in sickle cell patients but not in non-sickle patients. Impairment of fibrinolysis in most patients was not on the basis of overutilization or consumption, since no decrease in the levels of clotting factors or plasminogen was observed. It was suggested that generalized intravascular sickling in these patients may have caused widespread endothelial damage, resulting in decreased production of plasminogen activator.

In addition, several sickle cell patients with infection were found to possess elevated levels of an inhibitor directed against urokinase.
The Influence of Inhibitors of Plasmin and Plasminogen Activation on the Streptokinase-Induced Fibrinolytic State
Authors: Spöttl F , Holzknecht F
Published: June 2018

The influence of the inhibitors of plasminogen activation by streptokinase, urokinase and tissue activator and of the two antiplasmins i.e. α1 antitrypsin and α2-macroglobulin, upon the formation and clearance of streptokinase-activator in vivo was investigated in 22 subjects. No influence of the above mentioned inhibitors on the formation of the streptokinase-activator could be found, whereas the clearance of the activator seems to be a function of the α2-macroglobulin level before streptokinase administration. The clearance rate of the streptokinase-activator differed significantly from the clearance rate of 131I labelled streptokinase caused by antigen-antibody complex formation [Fletcher et al. (10)], and was similar to the clearance rate of the histamine or nicotinic acid induced plasminogen activator. The possibility of a common clearing mechanism of fibrinolytic activators is discussed.

The existence of 3 different inhibitors activities on plasminogen activation as tested in vitro i. e. inhibitor of streptokinase, urokinase and tissue activator, was demonstrated. These inhibitory activities are probably not the properties of 3 different serum proteins but rather the result of the action of α1antitrypsin and α2-macroglobulin. The degree of inhibition, however, of each of the 2 proteins on each of the 3 plasminogen activators (streptokinase, urokinase and tissue activator) seems to be different. This difference may be caused by a different inhibitory effect of α1 antitrypsin or α2-macroglobulin on each of the plasminogen activators.

The plasmin formed after the streptokinase infusion is rapidly bound by the α2macroglobulin and this plasmin-antiplasmin complex is immediately removed from the blood, causing a decrease of the α2-macroglobulin level. This decrease of α2-macroglobulin is correlated with the initial level of α2-macroglobulin. This finding demonstrates the concentration depending formation of the plasmin-antiplasmin complex also in vivo.
Severe Hereditary Deficiency of Factor VII during Pregnancy
Authors: Seligsohn U , Peyser M. R , Toaff R , Shani M , Ramot B
Published: June 2018

In normal pregnant women factor VII level is increased. This may also be observed in women with hereditary partial factor VII deficiency.

In a 38 year old woman with severe hereditary factor VII deficiency no change of the factor level was observed during pregnancy. The patient underwent two uneventful caesarian sections because of placenta praevia and transverse lie of the fetus.

During the second caesarian section factor VII level was simultaneously determined in blood obtained from the antecubital and uterine veins and from the umbilical vein and artery. Factor VII levels in the umbilical vessels were similar and exceeded the levels observed in the mother’s vessels. In 3 control patients similar examinations were performed during caesarian sections but reversed ratios of factor VII levels were observed. These data seem to prove that factor VII does not cross the placenta.

In the family study 2 siblings were found to have severe factor VII deficiency whereas several other members had either normal or partial deficient levels. The results obtained support again the assumption that factor VII deficiency is inherited by an autosomal gene that in the homozygous state is manifested by severe factor VII deficiency and in the heterozygous state by mild deficiency or normal factor VII levels.
Elevation of Factor VIII in Acute Fatal Liver Necrosis
Authors: Meili E. O , Straub P. W
Published: June 2018

1. During 1963–1967 we observed 9 patients with letal fulminant hepatitis and a usually massive elevation of plasma factor VIII activity in the presence of a severe depletion of all other coagulation factors.

2. Patient plasma, diluted to 100% factor VIII activity was equally effective as normal plasma in correcting the haemophilia A defect in various systems.

3. An artefact due to thrombin or other clotting intermediates has been excluded.

4. The following observations suggest an increase of factor VIII protein and not only of factor VIII activity : No difference was found between normal and patient factor VIII in their behaviour during heating, pH alteration, adsorption, plasmin digestion, ammonium sulfate and euglobulin precipitation, and neutralization by a specific factor VIII inhibitor. In contrast, factor VIII artifically activated in vitro with thrombin, was inactivated more rapidly by heat and plasmin than untreated normal or patient factor VIII.

5. The mechanism and possible causes for this factor VIII elevation are discussed. Factor VIII elevation is limited to the most severe cases and may therefore be of prognostic significance in liver dystrophy.
Studies on the Anticoagulant Action of Aprotinin (“Trasylol”)
Authors: Prentice C. R. M , McNicol G. P , Douglas A. S
Published: June 2018

Studies were undertaken to localize the site of the anticoagulant action of Aprotinin (“Trasylol”). Contact activation studies using either kaolin or contact product eluted from celite demonstrated that Aprotinin had greatest inhibitory action against the interaction of a surface with the contact factors, but some inhibition of formed contact product was also noted. In addition, Aprotinin was found to have a slight anticoagulant action against activated factor IX prepared by incubation of contact product with a calcium phosphate eluate from serum. No inhibitory action in pharmacological doses was demonstrated against activated factor X or later stages in the coagulation sequence.

It was concluded that Aprotinin is a relatively weak anticoagulant in doses liable to be obtained in vivo during therapeutic infusions.
Platelet Adhesiveness, Aggregation and Fibrinolysis after the Oral Administration of the Contraceptive “Lyndiol”
Authors: Farbiszewski R , Kurowska T
Published: June 2018

The adhesiveness and aggregation of platelets in plasma of women treated with “Lyndiol”, an anticonceptive agent, were investigated.

An increase of adhesiveness and enhancement of platelet aggregation induced by ADP and thrombin was observed. The pathophysiological significance of the described changes is briefly discussed.
Protection from Hg-Inactivation of Factor XIII by Mercaptalbumin
Authors: Fantl P
Published: June 2018

The blood plasma factor XIII (fibrin stabilizing factor) is inactivated by mercuric ions and can be reactivated by serum - or plasma albumin of which the active component is mercaptalbumin. A relation between mercaptalbumin concentration and factor XIII activity is pointed out.
Functional and Steric Characteristics of Modified Thrombin Zymogen
Authors: Marciniak Ewa
Published: June 2018

Steric and functional changes of thrombin zymogen, due to the degrading action of thrombin, have been studied. A prothrombin complex of a high degree of activity was obrained from bovine plasma by adsorption on BaCO3. This preparation was further purified by ion exchange chromatography and converted with a small amount of thrombin into a modified form of zymogen. The difference between the unmodified and modified form, with respect to their reactivity, has been seen only in a biological type of activation with factor Xa-phospholipid-factor V-calcium complex. The modified form, when reacting as a concentrated substrate, or the diluted one, under conditions of the two-stage analysis, required several-fold higher concentrations of factor V. With factor Xa alone as activating enzyme, both forms of zymogen reacted in exactly the same manner. Gel filtration studies indicated a drastic change in shape or size of the altered zymogen molecule, as defined by Stokes radii.

Factor X present in prothrombin complex preparations, by its frictional characteristic, obviously resembled the unmodified form of prothrombin. However, it was not affected by thrombin either in a functional way or in its molecular parameters. This indicates that, although present together in the same multiactivity preparation, factor X and thrombin zymogen do not form a molecular complex.
Mg++ - and Ca++-Induced Platelet Aggregation and ADP
Authors: Cronberg S , Caen J. P
Published: June 2018

Reports on platelet aggregation after addition of calcium or magnesium to EDTA- PRP or platelet suspensions were confirmed. An aggregating principle was found in the EDTA-plasma and the supernatant of the platelet suspensions. Aggregation by magnesium in a platelet suspension was inhibited by adenosine and phosphoenol- pyruvic acid and pyruvate kinase, which suggested that the active principle was identical with ADP. Degradation of ADP in EDTA plasma was blocked.

It thus appears that aggregation induced by calcium or magnesium in EDTA-PRP and platelet suspension was due to accumulation of spontaneously liberated ADP, which was not degraded.
Mechanism of Action of Synthetic Fibrinolytic Compounds
Authors: Baumgarten W , Priester L. I , Stiller D. W , Duncan A. E William
Published: June 2018

The mechanism of dissolution of a preformed plasma clot was explored.

Our experiments showed clearly that the purified fibrin clot, made by extensive washing of a plasma clot, was resistant to lysis and that the fibrinolytic potential of the active fibrinolytic compounds was related to the presence of other plasma proteins in addition to fibrinogen.

The activation of the fibrinolytic precursors was reversible inasmuch as removal of the fibrinolytic compounds negated the fibrinolytic activity of the protein-fibrinolytic compound mixture.

Antifibrinolytic compounds which had been shown to interfer with fibrinolysis by streptokinase-activated plasminogen inhibited dissolution of the preformed plasma clot by fibrinolytically active compounds.

The fibrinolytic potential of fibrinolytic compounds was additive; however, no apparent synergism was observed.

The implication of these results to the mechanism of synthetic fibrinolysis was discussed.
Thrombosis Prevention by Coagulation and Platelet Aggregation Inhibitors, in Hyperlipemic Rats
Authors: Renaud S , Lecompte F
Published: June 2018

Phenylbutazone, oxyphenbutazone, and sulfinpyrazone were equally effective at the dosage of 100 mg/kg (per os) in inhibiting thrombin- and ADP-induced platelet aggregation in hyperlipemic rats, and in preventing the development of thrombosis initiated by the intravenous injection of an endotoxin. Despite a slight anticoagulant effect of these substances, their antithrombotic activity appears to be due mostly to inhibition of platelet aggregation.

Thrombosis in hyperlipemic rats could also be prevented by a dicoumarol derivative, acenocoumarin, which only inhibits coagulation. Therefore, both platelet aggregation and fibrin formation appear to be essential for the occurrence of large thrombi under these conditions. Nevertheless, although acenocoumarin has no direct effect on platelet aggregation, it could indirectly affect this phenomenon by blocking the formation of thrombin, which is suspected of being the agent responsible for initiating thrombosis in hyperlipemic rats.

Low doses of phenylbutazone and acenocoumarin, in condition, which when given alone were ineffective in inhibiting thrombosis, could decrease the severity of thrombosis by 33%. The substance GP45840, when added in vitro to platelet-rich plasma as well as given per os to hyperlipemic rats, was no more effective than sulfinpyrazone in inhibiting platelet aggregation. Nevertheless, this substance was significantly more efficient in reducing thrombosis than was sulfinpyrazone, apparently through some additional anticoagulant activity. The results of these experiments suggest that it could be beneficial to affect both coagulation and platelet aggregation in order to satisfactorily prevent thrombosis.
The Induction of the Release Reaction in Human Blood Platelets by Close Cell Contact
Authors: Massini P , Lüscher E. F
Published: June 2018

When blood platelets are centrifuged at elevated pH they release serotonin. This reaction is similar to the release reaction which makes part of the complex called viscous metamorphosis. The experiments support the hypothesis that contact between platelets forms the stimulus which initiates the release reaction.
The Evaluation of a Method for Adenosine Diphosphate Induced Platelet Aggregation in the Guinea Pig
Authors: Mackenzie R. D , Henderson J. G , Steinbach J. M
Published: June 2018

A method is described for the in vivo measurement of ADP-induced platelet aggregation in the guinea pig. This method uses the property of the lungs to remove platelet aggregates from the circulation. ADP is infused into the jugular vein and blood samples are removed from the carotid artery for determination of platelet concentration.

In order to find a practical concentration of ADP and infusion time, the effects of several concentrations and infusion time on platelet count versus time were determined. A dose of 0.2 mg/kg ADP infused over 1 min was found to produce an approximately 50% drop in platelet count with a return to the original level at about 30 min. The analysis of the platelet response to ADP can be made quantitative by measurement of the total response, that is, the total decrease of platelet count from start of infusion to the return to preinfusion values.

Prostaglandin E1 was tested and found to inhibit the total aggregation response with this method.
Platelet Reactions and Immune Processes
Authors: Jobin F , Lapointe F , Gagnon F
Published: June 2018

We have studied the effect of IgG, IgA, IgM, lambda light chains, Fc fragments, heat-aggregated gammaglobulin, albumin and fibrinogen on the interaction of latex, Kaolin, celite or bentonite particles with human platelet-rich plasma.

1. Marked enhancement of platelet aggregating activity was produced by preincubating these particles with IgG at an appropriate concentration. Excess IgG abolished this platelet aggregating property.

2. Platelet aggregation could also be induced by betamethasone acetate particles. The latter and IgG-coated latex, Kaolin or bentonite particles were inhibited by chymotrypsin substrates and inhibitors.

3. Heat-aggregated IgG produced platelet aggregation in platelet-rich plasma only when adsorbed onto (Kaolin) particles.

4. Results obtained with fibrinogen-coated Kaolin suggest that the particles thus acquired a slightly increased platelet clumping activity.

5. The other proteins studied failed to enhance the platelet aggregating activity of Kaolin particles, and could even inhibit the formation of IgG-coated Kaolin particles able to readily aggregate platelets.