bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study Of The Antithrombotic Effect Of Aggregation Inhibitors, Heparin And Combinations With Heparin
Authors: Schlag G , Grünwald M , Redl H 
Published: July 2018

Experimental thrombosis was produced by the freezing method to investigate in a randomized prospective trial the antithrombotic effect of the platelet aggregation inhibitors EhO 26644 (EMD; 0,1 mg/kg b.w.), acetylsalicylic acid (ASA; 30 mg/kg b.w.), heparin (50 I.U./kg b.w.), the combination of heparin (50 I:U:/kg b.w.) and EMD (0,1 mg/kg b.w.) and the combination of heparin and dihydroergotamine (HDHE; 50 I.U. heparin/kg b.w. 0,005 mg DHE/kg b.w.). Experimental thrombosis was caused under general anesthesia by freezing the jugular veins for 2 minutes. Incidence and weight of thrombi were studied under control (saline 1ml/kg b.w.) and the antithrombotic regimes. Each group consisted of 20 rats with an average weight of 355 g.Results: All antithrombotic drug series differed significantly from the control series. The minimal rate of thrombus formation was found in the HDHE group (2/20 vs 18/20 in control), while heparin (4/20) alone showed better results than the series with the aggregation inhibitors (EMD 8/20, ASA 6/20) or the combination with EMD (5/20). The lowest weight of thrombi was found in the series heparin EMD, differing not significantly from HDHE. Thus regarding frequency of thrombosis and weight of thrombi the antithrombotic combination HDHE showed the best results from the 5 regimes.
PGI2 Production In Human Endothelial Cells Cultured In Diabetic And Nondiabetic Serum
Authors: Paton R C , Guillot R , Passa Ph 
Published: July 2018

Reduced levels of prostaglandin I2 (PGI2) may contribute to the platelet hyper-reactivity and vascular complications found in diabetes mellitus. This study compared PGI2 production (PGI2-like activity and 6-keto-PGF1α levels) by vascular endothelial cells cultured in the presence of serum from 15 diabetics with proliferative retinopathy (5 treated by surgical hypophysectomy) and 15 sex-matched nondiabetic controls. Endothelial cells from human umbilical veins were cultured in M199 with either 20 % diabetic or control serum. At confluence, cultures were washed and stimulated with 0.1 NIH u/ml bovine thrombin. After 2 min incubation, the supernatant was tested for i)PGI2-like activity on ADP- induced platelet aggregation, results expressed as % inhibition and ii) 6-keto-PGF1α by radioimmunoassay, results expressed as nmol/ml. There was a significant correlation between PGI2-like activity and 6-keto-PGF-1α levels (r 0.78, p<0.001). The liberation of PGI2 from endothelial cells from different umbilical cords varied, but both PGI2-like activity (mean± SEM 21.9± 4.8 vs 28.3± 5.1 p<0.05) and 6-keto-PGF-1α (3.15± 0.68 vs 3.95 ±0.91 nmol/ml, p <0.05)were significantly lower in superantant from cells cultured in the presence of diabetic compared to control serum. PGI2 production was not significantly different in cells cultured with serum from hypophysectomised and nonhypophysectomised diabetics.These results suggest that serum from diabetics with proliferative retinopathy contains factors which impair the release or production of PGI2 by endothelial cells and that this effect is not mediated by the pituitary.
The influence of microangiopathy in Diabetics with antiplatelet drugs
Authors: Bremer G , Richter O , Jacobi E , Koschinsky T 
Published: July 2018

It is well kown that microangiopathy is associated with shortened platelet survival. Therefore a pilot study was performed to test several antiplatelet drugs with respect to their ability to increase platelet survival. The study was confined to 18 patients with long standing Diabetes mellitus and microangiopathv of I.- II. degree, exhibiting platelet survival times less than 7 days. The patients were treated with antiplatelet drugs. Dipyridamole with several combination of Acetylsali- cylicacid (ASA) and Sulfinpyrazon.1. 225 mg Dipyridamole and 990 mg ASA per day,
2. 225 mg Dipyridamole and 300 mg ASA per day,
3. 150 mg Dipyridamole and 150 mg Sulfinpyrazon
per day.Platelet survival was determined by the method described by Harker. The resultant survival curves were analysed by a computer program written by Murphy and Francis which is based on the multine hit model for platelet survival.The results of the study are: After 10 days treatment the platelet survival was markedly increased under each of the combination.If one assumes that there exists a causal relationship between microangiopathy and platelet survival,a long-term treatment by antiplatelet drugs may be a prophylaxis against microangiopathy in diabetics.
Adherent Mononuclear Cells And Activated Protein C (APC)
Authors: Taylor F B , Esmon C T , Carroll R C , Lockhart M L 
Published: July 2018

Addition of bovine APC to dilute whole blood or euglobulin assays of fibrinolytic activity produces little effect on rates of clot lysis. However, addition of APC to undiluted non anti coagulated or to 3.2% citrated whole blood followed by 125I-fibrinogen and thrombin produces clots which release fibrin degradation products and lyse within 24 hours. Ordinarily clotted non-anticoagulated whole blood does not lyse.Addition of increasing amounts of APC from 12-100ug/ml increases the rate of whole blood clot lysis at least 20 fold over a 3.2% citrate control. This response is dose dependent with no evidence of saturation. Addition of increasing amounts of APC (25-200ug/ml) to platelet poor plasma (PPP) increases the rate of clot lysis only twofold. This increase is also dose dependent but is saturated at 80-100ug/ml. Addition of APC (60ug/ml) to 3.2% citrated PPP plus adherent mononuclear cells (1,000-2,000/MM3) again increases the rate of clot lysis at least 20 fold as with the whole blood system. However, this increase in rate is delayed. Substitution of platelet rich plasma (PRP) for PPP eliminates the lag phase. Substitution of non-adherent cells (1,000 MM3), RBC (3 million/MM3) or polymorphonuclear cells produces no acceleration of PPP clot lysis above the PPP-APC control. When deoxyglucose (1.4 × 10-1M) and anti-mycin (2.9 × 10-5M) are added to the PPP plus adherentxells before APC, the cell dependent acceleration of clot lysis is abolished. Removal of plasminogen activator (PA) and plasminogen (P) from PPP by lysine agarose adsorbtion also inhibits the effect of APC and adherent cells whereas reconstitution restores activity to 60%.We conclude that adherent mononuclear cells are required for expression of optimal APC pro-fibrinolytic activity and that this may require both P and PA. This suggests another role for mononuclear cells (monocytes) found in inflamatory and thrombotic lesions.
Effect Of Activated And Non-Activated Protein C On Mouse Tumor Metastases
Authors: Gasic T B , Catalfamo J L , Gasic G J 
Published: July 2018

Platelet aggregation (PA) and fibrin deposition appears to be involved in the establishment of blood-borne tumor cells as metastases. Since it has been reported that activated Protein C have fibrinolytic activity or can inhibit coagulation, we investigated whether activated Protein C may inhibit tumor spread. Preliminary studies in the mouse system indicated that (a) activated Protein C prolonged the kaolin cephalin clotting time of plasma treated in vitro (>10min.)or of plasma obtained from in vivo treated mice (55 vs 30 sec.), (b) activated Protein C can inhibit PA by plasma membrane vesicles shed by metastasizing tumor cells; this effect was much greater with rat gel filtered platelets than with heparinized mouse PRP. The inhibition effect was also present in vivo, since 56 ug of activated Protein C, injected ip 15 min. before iv injection of tumor vesicles (200 ug protein), reduced significantly thrombocytopenia and signs of respiratory sickness produced by the vesicles.After these studies, activated Protein C, as well as nonact ivated Protein C, was given ip 15 min. and 3 hr after iv inoculation of 5×104 MCA mouse sarcoma tumor cells. Three weeks later mice were killed and lung tumors sized and counted. The data shown in the Table (average and range) indicate that activated Protein C decreases metastasis, while Protein C increases both the size and the number of tumors.While the presumptive effect of activated Protein C on metastasis might be related to its anticoagulant and antiplatelet activities, we know nothing how Protein C enhances metastases in our experiments.
Generation Of Factor XII-Dependent Plasminogen Activator Activity In Human Plasma Measured With A Fluorogenic Substrate
Authors: Dooijewaard G , Kluft C 
Published: July 2018

A rapid fluorometric assay for measurement of amidolytic activity in human plasma was developed, using the plasminogen activator sensitive synthetic substrate t-BOC-L-valyl--glycyl-L-arginine-β-naphthylamide. The plasma is diluted in a reaction cuvet containing 0.050 M Tris HC1 buffer (pH 8.0) and 150 μM substrate. Activation of plasminogen proactivator(s) is initiated at 37°C by the addition of 10 μg dextran sulphate (MW 500,000)/ml. The concentration of β-naphthyl- amide released is recorded fluorometrically as a function of time. The slope of this curve at any time t is proportional to the concentration of activator. Thus, in a single assay, the entire time-dependent profile of activation and subsequent inhibition is monitored; this provides 1. a value for an optimum plasminogen activator content in the plasma, and 2. the time it takes to reach the optimum. The plot of optimum activator content against μl of plasma added is linear for dilutions more than 100-fold, suggesting that under these conditions the optimum content approaches the content of proactivator(s) originally present.The activator content measured predominantly consists of contributions of a factor XII-dependent process since 1. without dextran sulphate or with plasmas deficient in factor XII or prekallikrein no activity could be generated, and 2. plots of optimum activator content against dextran sulphate concentration show sigmoidal-shaped saturation curves as found previously for the kallikrein generation in human plasma. Contributions of factor XIIa and kallikrein only partly account for the content measured and studies with plasmas deficient in factor XI point to a minor role for this factor, if any. Further identification of the activator (s) involved is in progress.
Tolerancy Of Animal Fibrinolytic System To Exogenous Plasminogen Activator
Authors: Andreenko G V , Shimonaeva E E , Lyutova L V 
Published: July 2018

Our previous studies showed that intravenous injection of tissue plasminogen activator (TPA) from pig heart to albino rats causes lysis of artificial clots in v.jugularis. This is concomitant with a short-term increase in the fibrinolytic activity (FA) of the euglobulin fraction of blood plasma. The other components of the fibrinolytic system remain thereby unchanged.We tested the state of the fibrinolytic system at increasing concentrations of TPA and under varying conditions. A repeated (2-fold) injection of TPA did not further increase FA. When TPA was injected 4 times, the antiactivator and the level of TPA in the plasma of test and control animals decreased. This can be due to exhaustion of endogenous plasminogen activator as a stress response to repeated fixation of animals for intravenous injection of TPA. Injection of the same amount of TPA for 5 days caused no significant changes in FA. After a single injection of a 5-fold amount of TPA the changes were more noticeable; fibrinogen concentration was slightly decreased, whereas plasma recalcification time was increased. Thus, administration of exogenous TPA causing clot lysis has no prolonged effect on FA, which can be either due to its rapid release from the blood stream or to its binding to blood proteins.
The Preventive Effect Of The Polyunsaturated Fats On Thrombosis
Authors: Yotakis L D O 
Published: July 2018

The fact of thrombosis, mainly the case of coronaritis, was examined in regard of a diet consisting of polyunsaturated fats by use of two dietary differing populations. The representative groups consisted respectively of (70) and (80) persons of the age-groups 45-55, selected by random process between males as generally females suffer a lower incidence of cardial thrombosis than men.The first group concerned the universe of pure frugal meal, consisting of polyunsaturated fats, such as linon, linolen and arachidon acids having double bonds. The related population consisted of Gypsies and certain Coastal inhabitants the food of whom is obtained from vegetables, fishes and marine animals, containing the mentioned fats.The second sample was selected between well-fed and gluttonous individuals, representing the population of frequent coronaritis and thrombotic myocardium infarctus.42 attacks of thrombosis were observed among the 80 persons of the so-called well-fed sample; consequently the incidence-rate was 52 per cent. On the other hand the reciprocal rate concerning the frugal diet was equal to 3 per cent, as only 2 cases of attack were observed between Gypsies and the Coastal inhabitants. The rate of the two groups together was 29%. All other factors such as psychic stress, etc., being equal, the difference in thrombosis between the two populations 52 - 3 = 49 per cent is significant, as by means of the standard error of difference equal to 7 we observed that it is more than might occur by chance. The results of the investigations suggested that the polyunsaturated fats provoking and converting certain antiaggregating bodies and the vasoactive prostaglandins as well as a representative diet are efficient to the prevention of thrombosis.
Role Of Platelet cAMP And Prostaglandin Synthesis In Platelet Aggregation Inhibition By Ticlopidine Hydrochloride
Authors: Bruno J J , Yang D , Taylor L A , Feamster C 
Published: July 2018

Ticlopidine hydrochloride (T), 5-[(2-chlorophenyl) methyl]-4,5,6,7-tetrahydrothieno [3,2-c] pyridine hydrochloride, is a potent antiplatelet agent of unknown mechanism of action. T does not inhibit human platelet low Km, cAMP phosphodiesterase (PDE) in vitro, (IC50>>10-3M), but does have some activity versus the low Km, cGMP-PDE (IC503-4×10-4). Equivalent values for theophylline, a weak PDE inhibitor, are 1.6×10-4M and 4.2×10-4M, respectively. T has no synergistic effect in vitro on platelet aggregation inhibited by PGE1. PDE inhibitors do show synergism with PGE1 and other antiaggregatory PGs. Ex vivo in humans and animals, T inhibits ADP-induced aggregation. This inhibition is not altered by addition of SQ-22536 (f.c.-10-4M), a purported inhibitor of adenylate cyclase activity, whereas drugs whose platelet inhibitory activity depend on elevation of platelet cAMP, e.g., PGE1, adenosine and dipyridamole, have this inhibition partially reversed by SQ-22536.PG synthesis is not required for the antiplatelet activity of T. Addition of aspirin (f.c.-5×10-4M) in vitro to PRP from humans treated with T (500 mg/day) did not modify the aggregation response to ADP. In addition, PGI2 is not essential for the antiaggregation effect of T.The inhibition of ADP-induced aggregation of PRP prepared from blood of T-treated humans just after collection and more than 30 minutes after, to allow for inactivation of PGI2 were identical.We conclude that neither elevated cAMP nor PG synthesis is essential for T activity.
Potentiation Of Anti-Aggregating Prostaglandins By Ticlopidin
Authors: Bonne C , Martin B , Regnault F 
Published: July 2018

Ticlopidin (T) is a potent inhibitor of platelet aggregation which enhanced the platelet sensitivity to anti-aggregating prostaglandins such as PGE1. The goal of this study was to examine the site of action of T in the rat platelets after in vivo administration, in respect to the PGE1 mechanism of action.Male adult Wistar rats were orally administered at the dose of 200 mg/kg, 20 and h hours before blood collection. The binding of (3H)-PGE1 to platelets from controls and treated rats was determined by filtration technique. The c AMP formation was measured by protein binding assay in aspirin-washed platelet suspension or in lysate after stimulation by PGE1, adenosine or NaF.Since potentiation of PGE1 by T occured in aspirin-washed platelets, it is independent of the ability of the cells to synthesise prostaglandins. On the other hand, PGE1-receptor binding is not affected by T treatment and potentiation of PGE1 effect is not specific. Moreover, basal adenylate cyclase activity is increased in platelet particulate fraction of treated rats, but NaF stimulation is not enhanced.These results suggest that T activates the adenylate cyclase systems by an action on the coupler subunit of the enzyme just as guanosine triphosphate does.
Antiplatelet Effect Of A New Compound, Imidazo[1,2-a]- Thienopyrimidin-2-One : A Cyclic AMP Mediated Phenomenon
Authors: Ashida S , Sakuma K , Abiko Y 
Published: July 2018

The effect of a new compound, 1,2,3,5,6,7,8,9-Octahydro- [1]benzothieno[2,3-d]imidazo[1,2-a]pyrimidin-2-one hydrochloride (DH-6471), on cAMP metabolism and aggregation of platelets was studied. In vitro. DH-6471 inhibited platelet aggregation (both the 1st and 2nd phases) induced by ADP, collagen, thrombin, arachidonic acid and PGG2-TXA2 mixture in PRP from various animal species including human at concentrations (IC50) ranging from 0.07 to 8 μH. It inhibited ADP- and collagen-induced platelet aggregation ex vivg in rats following oral doses as low as 0.3- 1 mg/kg.The compound was found to be a highly selective inhibitor of platelet low Km cAMP phosphodiesterase (Ki=0.025 μM), when tested with enzyme fractions separated by DEAE-cellu-lose chromatography. It did not significantly affect basal or PGE1(0.1-1 μM)-stimulated cAMP level of platelets at a concentration of 1 μM where platelet aggregation and the low Km PDE were markedly inhibited. However, both basal and PGE1-stimulated accumulations of cAMP in the platelet membrane fraction were increased by DH-6471 at 1 μM when the isolated membrane fraction was incubated with ATP-Mg2+.Studies with several PDE inhibitors including papaverine, dipyridamole and DH-6471-related compounds showed a close correlation between their ability to inhibit the low Km PDE or to increase cAMP accumulation in the membrane fraction and their inhibitory effect on platelet aggregation. On the other hand, their potency to inhibit high Km cAMP-PDE(cGMP-PDE) and to increase cAMP level in whole platelets was poorly correlated to their inhibitory activity in platelet aggregation.These results suggest that some small but local changes in platelet cAMP may be involved in the regulation of platelet aggregation, particularly primary aggregation.
Deposition Of Fibrin, Fibrinogen And Platelets On The Sub- Endothelium Of Ex Vivo Perfused Rabbit Aorta
Authors: Neftel K , Baumgartner H R , Haeberli A , Straub P W 
Published: July 2018

The subendothelium of 2 cm segments of rabbit aorta was exposed to human blood flowing directly from an antecubital vein under controlled conditions, the flow being 10 and 20 ml/min., the perfusion time varying between 1 and 10 min.. One cm of aorta taken from the middle of the segment was incubated with plasmin until proteolysis of fibrin and fibrinogen was completed. From quantitative measurements of the proteolytic fragment E, the sum of fibrinogen + fibrin was calculated (J.Lab. Clin. Med. 96:258,1980). The proteo- lysate was then incubated with thrombin, the released fi-brinopeptide A determined using a RIA and the fibrinogen of the deposits calculated. In addition, fibrin and platelets deposition were estimated morphometrically on the adjacent distal and proximal part of the segments.1. Fibrin deposits varied between 1.4 and 82.6 ug. At a flow of 10 ml/min. fibrin deposition increased7 with increasing perfusion time; at 20 ml/min. no time dependence was observed.
2. Platelet adhesion, deposited platelet volume and thrombus height increased with time at both flew rates.
3. Fibrinogen varied between 1.4 and 7 ug. In contrast to fibrin maximal levels were reached witnin one minute.Thus, in the ex vivo system fibrin deposition was dependent on flow and with the lower flow rate also on perfusion time. In contrast, the observed fibrinogen was probably due to unspecific adsorption.
Thrombin-Induced Release Of Adenine Nucleotides From Cultured Human Endothelial Cells
Authors: Lollar P , Owen W G 
Published: July 2018

The effect of thrombin on the release of adenine nucleotides from cultured human umbilical vein endothelium was studied. When endothelial cell monolayers were incubated with 3H-adenosine for two hours at 37°C, fifty percent of the radioactivity was incorporated into the cell. Thin-layer radiochromatography revealed that greater than 90% of the tritium was associated with ADP and ATP.Addition of thrombin to the monolayers resulted in the release of tritium into the medium. This effect was dose-dependent and saturable, with a maximal response seen at 1 × 10-8 M thrombin. Diisopropylphosphoryl thrombin (DIP-thrombin) , which is enzymatically inactive, did not cause a release of tritium. Blocking the high-affinity thrombin binding sites which are present on the endothelial cell surface was done with DIP-thrombin. Saturating these binding sites by greater than 95% with a fifty-fold excess of DIP-thrombin had no effect on thrombin-induced release, indicating that the high-affinity binding sites are not involved in the release of adenine nucleotides by thrombin.
Structural Studies On Glycocalicin
Authors: Jamieson G A 
Published: July 2018

When platelets are homogenized, a major membrane glycoprotein component (Mr 150,000) which has been termed glycocalicin, appears in the supernatant in soluble form. Immunological studies in several laboratories suggest that glycocalicin is derived from glycoprotein Ib (Mr 200,000) by the action of a Ca++ - dependent protease released from the platelet.Glycocalicin has been purified to homogeneity by conventional procedures as well as by a two step procedure utilizing affinity chromatography on insolubilized wheat germ agglutinin and insolubilized thrombin. Purified glycocalicin has been shown to inhibit platelet aggregation induced by thrombin and by ristocetin.The molecule is cleaved by trypsin to a macroglyco- peptide (Mr 120,000) in which biological activity has not been detected, and a peptide “tail” (Mr 45,000), which is a competitive inhibitor of the binding of thrombin to intact platelets.Intact glycocalicin contains ∼ 60% carbohydrate comprising Gal, GalNAc, GluNAc and NeuNAc in the ratio 2:1:1:2. The macroglycopeptide contains virtually all of this carbohydrate. Only trace amounts of carbohydrate are found in the tail peptide but serine, glycine and glutamic acid comprise over half the amino acid residues. Glycocalicin in intact platelets is resistant to iodi- nation but is readily iodinated following isolation both in the macroglycopeptide and tail peptide portions of the molecule.The ready availability of purified glycocalicin may be of value in elucidating structure-function relationships of glycoprotein Ib and its orientation in the platelet membrane.