The Action of an Aniline Derivative (AN 162) on Blood Coagulation and on Platelets

1971 ◽  
Vol 26 (01) ◽  
pp. 145-166
Author(s):  
E Deutsch ◽  
K Lechner ◽  
K Moser ◽  
L Stockinger
Keyword(s):  
Blood Coagulation ◽  
Citric Acid Cycle ◽  
Second Phase ◽  
Aniline Derivative ◽  
Acid Cycle ◽  
Enhancing Effect ◽  
Low Concentrations ◽  
Dual Action ◽  
High Concentrations ◽  
Induced Aggregation

Summary1. 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.

scholarly journals Effects of a Polyoxyethylene Detergent on Platelet Function

1977 ◽  
Author(s):  
P.G. Barton
Keyword(s):  
Lactate Dehydrogenase ◽  
Platelet Rich Plasma ◽  
Secondary Phase ◽  
Human Platelets ◽  
Brij 58 ◽  
Low Concentrations ◽  
High Concentrations ◽  
Glass Surfaces ◽  
Induced Aggregation ◽  
Membrane Destabilization

Low concentrations of a polyoxyethylene detergent, Brij 58, inhibited the secondary phase of platelet aggregation induced by ADP in human citrated platelet rich plasma but had no effect on primary aggregation.Thrombin-induced aggregation of washed human platelets suspended in Tyrode’s buffer was inhibited after incubation of cells with 4.5 × 10-6M detergent. Development of prothrombin-converting activity and efflux of [14C]-serotonin, 45Ca2+ ions and labile endoperoxides were abolished concomitantly. Aggregation of washed platelets by collagen or sodium arachidonate and the attachment of cells to clean glass surfaces were also inhibited by the same concentration of Brij 58 that inhibited thrombin aggregation. This concentration of Brij 58 did not itself produce any release of a cytoplasmic marker, lactate dehydrogenase, from platelets. Higher concentrations of Brij 58, exceeding 10-4 M, lysed the cells liberating all of their serotonin, Ca2+ and lactate dehydrogenase. These results suggest that low concentrations of Brij 58 stabilize a membrane conformation against the action of platelet stimulatory agents while high concentrations produce membrane destabilization and cell lysis. The presence of albumin (BSA) in the suspending fluid increased by tenfold the concentrations of detergent required to “elicit these effects and this could be attributed to competitive binding of the detergent to albumin, demonstrated with [14C]-acetylated Brij 58.

Observed differences in dextran and polyvinylpyrrolidone as rouleaux-inducing agents

1980 ◽  
Vol 58 (3) ◽  
pp. 271-274 ◽  
Author(s):  
Lionel S. Sewchand ◽  
Dieter Bruckschwaiger
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Animal Species ◽  
Critical Concentration ◽  
Rbc Membrane ◽  
Low Concentrations ◽  
High Concentrations ◽  
Induced Aggregation ◽  
Do So

The effectiveness of dextran fractions (Dx-500, Dx-100, Dx-70) and polyvinylpyrrolidone (PVP-360, PVP-40) in inducing aggregation of red blood cells (RBC) was studied in a nonflowing environment. The Dx fractions, at low concentrations, induced aggregation of human RBC but failed to do so at high concentrations (concentrations greater than 70 g/L). The effect was different on RBC from animal species (cat and rabbit); aggregation increased steadily with the Dx concentration and there was no critical concentration beyond which Dx failed to induce aggregation. The PVP was found to be very effective, at all concentrations, in inducing aggregation of RBC from both human and the animal species. These results have a twofold significance: (1) they suggest that Dx and PVP, both neutral polymers, interact differently with the human RBC membrane; and (2) the association of Dx with the human RBC membrane is different from that with cat and rabbit RBC membranes.

scholarly journals Abnormalities of factor VIII and platelet aggregation--use of ristocetin in diagnosing the von Willebrand syndrome

Blood ◽  
1975 ◽  
Vol 45 (3) ◽  
pp. 403-412 ◽  
Author(s):  
HJ Weiss
Keyword(s):  
Platelet Aggregation ◽  
Factor Viii ◽  
Platelet Rich Plasma ◽  
Second Phase ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Low Concentrations ◽  
Platelet Defects ◽  
Von Willebrand ◽  
Induced Aggregation

Ristocetin was used to study platelet aggregation in platelet-rich plasma and to assay the von Willebrand factor activity of factor VIII (VIII-VWF). Ristocetin-induced platelet aggregation (RIPA) was decreased in 13 of 18 patients with von Willebrand's disease (VWD) who had decreased plasma levels of VIII-VWF. The five patients with normal RIPA appeared to have mild VWD but did not constitute a separate subclass. RIPA was also abnormal in some patients with intrinsic platelet defects, but in no case was the defect corrected by normal plasma. The latter type of correction appears to be specific for VWD. Aspirin ingestion inhibited the second phase of RIPA (at low concentrations of ristocetin only) but did not affect the initial phase of aggregation or the level of VIII-VWF. We also studied a group of patients who had both abnormalities of the factor VIII complex and intrinsic platelet defects, such as impaired collagen-induced aggregation, as well. The findings in these patients and in those with typical von Willebrand's disease appear to comprise a spectrum of disorders (the von Willebrand syndrome) in which some abnormality of the factor VIII complex is associated with impaired platelet function. At present, ristocetin would appear to be a useful reagent for evaluating patients with bleeding disorders and for studying patients with the von Willebrand syndrome.

Inhibition of PAR4 Signaling in Ethanol-Attenuation of Platelet Function.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3892-3892
Author(s):  
Shogo Kasuda ◽  
Yoshihiko Sakurai ◽  
Midori Shima ◽  
Masahiro Takeyama ◽  
Katsuhiko Hatake ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Phospholipase A2 ◽  
Platelet Activation ◽  
Platelet Function ◽  
Phase Curve ◽  
Peak Time ◽  
Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations ◽  
Induced Aggregation

Abstract Background: Moderate consumption of alcohol beverages reduces the morbidity from coronary heart disease. Previous studies describing of inhibitory activity of ethanol (EtOH) on platelet function have substantiated this observation. However, the effects of EtOH on thrombin-related platelet activation remains to be fully elucidated, though platelet activation by thrombin is essential for normal hemostasis as well as relevant to pathophysiological conditions of thrombosis. Objectives: The aim of this study is to elucidate the effect of EtOH on α-thrombin-related platelet function by measuring platelet aggregation and intracellular calcium ([Ca2+]i). Materials and Methods: A dual-wavelength spectrofluorometer was used for measurement. α-thrombin, PAR1-activating peptide (AP) (10 μM) or PAR4-AP (25 μM) was added to fura2-AM loaded washed platelet preincubated with or without EtOH (40, 80, 160 and 320 mM). Results and Interpretations: First, the effects of EtOH on 0.5 nM of thrombin-induced platelet activation was assessed. The concentration 0.5 nM used is conceived to activate platelets only via PAR-1. EtOH did not affect platelet aggregation. EtOH inhibited rise of [Ca2+]i dose-dependently. [Ca2+]i peak time at which maximal rise of [Ca2+]i delayed in a dose-dependent manner. Secondly, 10 nM of thrombin was used as an agonist. Stimulation by high concentrations of thrombin (〉 5nM) results in cleavage of both PAR1 and PAR4. The changes in [Ca2+]i showed double-phase curve composed of transient spike and prolonged peak in the absence of EtOH. Although EtOH inhibited neither platelet aggregation nor the first phase of [Ca2+]i increasing, it reduced the second prolonged elevation of [Ca2+]i dose-dependently. To elucidate the inhibiting mechanism of EtOH more precisely, the effects of EtOH on PAR1-AP-induced platelet function were examined. Rise of [Ca2+]i gave a spike form and was almost unchanged even in the presence of high concentrations of EtOH, whereas platelet aggregation was reduced and dissociated in the presence of EtOH. Lastly, the effects of EtOH on PAR4-AP-induced platelet function was examined. Aggregation of PRP was quenched by high concentrations of EtOH but dissociation was not observed contrary to that observed in PAR1-AP-induced aggregation. Further, EtOH inhibited [Ca2+]i rise and delayed [Ca2+]i peak time dose-dependently. Our results provided a possible mechanism by which EtOH inhibits platelet activation. Reduction of the prolonged elevation of [Ca2+]i by high concentrations of thrombin suggested that EtOH inhibits PAR4 signaling not PAR1 since the second prolonged phase of [Ca2+]i is mediated by PAR4. Inhibition of PAR4-induced aggregation and [Ca2+]i elevation by EtOH supported the findings and EtOH might reduce Ca2+ influx through inhibition of PAR4. Furethermore, the difference between the platelet activation mechanisms of low concentrations of thrombin and PAR1-AP was suggested. PAR1-AP can aggregate platelets at least but might fail to activate phospholipase A2 required for sustaining stable aggregation since EtOH abolishes phospholipase A2 and thereby reduces thromboxane A2 generation. On the other, thrombin at low concentrations might have another pathway for activating platelet differently than PAR1-AP. Further characterization of the mechanisms involved in inhibition of platelet activation by EtOH may help develop new strategies to control thrombin-mediated platelet activation.

scholarly journals Production of tricarballylic acid by rumen microorganisms and its potential toxicity in ruminant tissue metabolism

1986 ◽  
Vol 56 (1) ◽  
pp. 153-162 ◽  
Author(s):  
James B. Russell ◽  
Neil Forsberg
Keyword(s):  
Citric Acid ◽  
Citric Acid Cycle ◽  
Competitive Inhibitor ◽  
Rumen Microorganisms ◽  
Aconitate Hydratase ◽  
Factors Affecting ◽  
Acid Cycle ◽  
Rat Liver Cells ◽  
High Concentrations

1. Rumen microorganisms convert trans-aconitate to tricarballylate. The following experiments describe factors affecting the yield of tricarballylate, its absorption from the rumen into blood and its effect on mammalian citric acid cycle activity in vitro.2. When mixed rumen microorganisms were incubated in vitro with Timothy hay (Phleum praiense L.) and 6.7 mM-trans-aconitate, 64 % of the trans-aconitate was converted to tricarballylate. Chloroform and nirate treatments inhibited methane production and increased the yield of tricarballylate to 82 and 75% respectively.3. Sheep given gelatin capsules filled with 20 g trans-aconitate absorbed tricarballylate and the plasma concentration ranged from 0.3 to 0.5 mM 9 h after administration. Feeding an additional 40 g potassium chloride had little effect on plasma tricarballylate concentrations. Between 9 and 36 h there was a nearly linear decline in plasma tricarballylate.4. Tricarballylate was a competitive inhibitor of the enzyme, aconitate hydratase (aconitase; EC 4.2.1.3), and the inhibitor constant, KI, was 0.52 mM. This KIvalue was similar to the Michaelis-Menten constant (Km) of the enzyme for citrate.5. When liver slices from sheep were incubated with increasing concentrations of tricarballylate, [I4C]acetate oxidation decreased. However, even at relatively high concentrations (8 mM), oxidation was still greater than 80% of the maximum. Oxidation of [I4C]acetate by isolated rat liver cells was inhibited to a greater extent by tricarballylate. Concentrations as low as 0.5 mM caused a 30% inhibition of citric acid cycle activity.

HIGH CONCENTRATIONS OF HEPARIN ARE MORE INHIBITORY TO PLATE- AGGREGATION IN-VITRO THAN ARE LOW MOLECULAR WEIGHT HEPARINS AND HEPARINOIDS AT THE SAME CONCENTRATION

1987 ◽  
Author(s):  
H Messmore ◽  
B Griffin ◽  
J Seghatchian ◽  
E Coyne
Keyword(s):  
Molecular Weight ◽  
Heparan Sulfate ◽  
Dermatan Sulfate ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Low Molecular Weight ◽  
Low Concentrations ◽  
High Concentrations ◽  
Induced Aggregation

Other investigators have shown that heparin in the usual therapeutic range (0.1-0.5 units/ml) has an enhancing effect on ADP aggregation and an inhibitory effect on collagen and thrombin induced aggregation. The effects of low molecular weight heparin (LMWH)and heparinoids (dermatan sulfate, heparan sulfate) on platelet aggregation have not been as extensivelystudied. We have utilized citrated platelet rich plasma (3.2%citrate-whole blood 1:9) drawn in plastic and adjusted to a final platelet count of 250,000/ul. A Bio-Data 4 channgl aggregometer was utilized with constantstirring at 37 C. The reaction was allowed to run for 20 minutes. Platelet rich plasma was supplemented 1:9 with saline or heparin and various agonists were then added ifno aggregation occurred. ADP, collagen, thrombin, ristocetin and serum from patients with heparin inudced thrombocytopenia (HIT) were utilized as agonists. Heparin was substituted at concentrations of 0.1 to 500 units per ml and various LMWH and heparinoids were substituted in equivalent anti-Xa or gravimetric concentrations. At low concentrations no inhibitory effect on any ofthe agonists was observed with any of the heparins or heparinoids. At concentrations of heparin of 100 u/ml or greater, all agonists were inhibited. At equivalent concentrations of five different LMWH (Cy 216, Cy 222, Pk 10169, Kabi 2165 and pentasaccharide) inhibition did notoccur at all or at very high concentions only. Dermatan sulfate and heparan sulfate inhibited only at high concentrations. HIT serum could not aggregate platelets with dermatan sulfate or pentasaccharide atany concentrations, but it was a good agonist with the other heparins and heparinoids.

scholarly journals Some properties of mitochondria isolated from the flight muscle of the periodical cicada, Magicicada septendecim

1971 ◽  
Vol 121 (5) ◽  
pp. 771-780 ◽  
Author(s):  
R. G. Hansford
Keyword(s):  
Flight Muscle ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Low Concentrations ◽  
Mammalian Mitochondria ◽  
High Concentrations ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Simple Summation ◽  
Periodical Cicada

Mitochondria from the flight muscle of the periodical cicada oxidize pyruvate and d-glycerol 1-phosphate at rates comparable with those obtained with flight-muscle mitochondria from other insects. The oxidation of d-glycerol 1-phosphate is greatly stimulated by low concentrations of Ca2+. However, oxidative phosphorylation with this substrate is optimum over only a narrow range of Ca2+ concentration, because of the ability of these mitochondria actively to accumulate Ca2+ present at micromolar concentrations. The oxidation of pyruvate via the complete tricarboxylic acid cycle is enhanced by high concentrations of phosphate. When both pyruvate and d-glycerol 1-phosphate are present simultaneously, there is no simple summation of the rates obtained with the substrates singly. Acetyl-l-carnitine, palmitoyl-l-carnitine, glutamate and 2-oxoglutarate are oxidized at rates similar to those obtained with mammalian mitochondria, though lower than those obtained with the two prime substrates. However, no other tricarboxylic acid-cycle intermediates added to the medium were oxidized. From these and other observations it has been concluded that these mitochondria possess a previously undescribed combination of substrate-anion permeases.

Factors Influencing the Deaggregation of Human and Rabbit Platelets

1983 ◽  
Vol 49 (03) ◽  
pp. 162-167 ◽  
Author(s):  
R L Kinlough-Rathbone ◽  
J F Mustard ◽  
D W Perry ◽  
E Dejana ◽  
J-P Cazenave ◽  
...  
Keyword(s):  
Human Platelets ◽  
Release Reaction ◽  
Factors Influencing ◽  
Platelet Adherence ◽  
Activated Platelets ◽  
Fibrinogen Binding ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
Induced Aggregation

SummaryThe mechanisms involved in platelet deaggregation are unclear. Washed platelets from rabbits or humans aggregated by ADP can be deaggregated by EDTA or PGI2 if the release reaction has not occurred; during deaggregation 125I-fibrinogen dissociates from the platelets. Human platelets suspended in a medium without calcium undergo the release reaction during ADP-induced aggregation; EDTA, PGE, or PGI2 do not deaggregate these platelets although EDTA displaces much of the 125I-fibrinogen that associates with them during aggregation. Rabbit platelets aggregated by low concentrations of releaseinducing stimuli (sodium arachidonate, collagen or thrombin) can be deaggregated by EDTA, PGI2 or PGE1 and 125I-fibrinogen dissociates from them; with high concentrations of collagen or thrombin, deaggregation and dissociation of l25I-fibrinogen is slower. Human platelets that have undergone the release reaction in response to thrombin, collagen or a combination of sodium arachidonate and ADP are not readily deaggregated by EDTA or PGE1. Since aggregation and fibrinogen binding involving the glycoprotein IIb/IIIa complex are readily reversed by EDTA, and since Ca2+ is required for thrombospondin binding to activated platelets, there may be a third type of platelet-platelet adherence that is not disrupted by EDTA; this type of binding plays a greater role with human than with rabbit platelets.

scholarly journals The inhibition of β-lactamases from Gram-negative bacteria by clavulanic acid

1981 ◽  
Vol 199 (3) ◽  
pp. 779-787 ◽  
Author(s):  
Christopher Reading ◽  
Tony Farmer
Keyword(s):  
Clavulanic Acid ◽  
Major Product ◽  
Stable Complex ◽  
Second Phase ◽  
Complete Inactivation ◽  
Low Concentrations ◽  
Stable Species ◽  
High Concentrations ◽  
Rates Of Decay ◽  
Inhibited Enzyme

The β-lactamase from Klebsiella pneumoniae E70 behaved in a similar fashion to the TEM-2 plasmid mediated enzyme on reaction with clavulanic acid. Both enzymes produced two types of enzyme–clavulanate complex, a transiently stable species (t½=4min at pH7.3 and 37°C) and irreversibly inhibited enzyme. In the initial rapid reaction (2.5min) the enzymes partitioned between the transient and irreversible complexes in the ratios 3:1 for TEM-2 β-lactamase and 1:1 for Klebsiella β-lactamase. Biphasic inactivation was observed for both enzymes and the slower second phase was rate limited by the decay of the transiently stable complex. This decay released free enzyme for further reaction with fresh clavulanic acid, the products again partitioning between transiently stable and irreversibly inhibited enzyme. This cycle continued until all the enzyme had been irreversibly inhibited. A 115 molar excess of inhibitor was required to achieve complete inactivation of TEM-2 β-lactamase. Hydrolysis of clavulanic acid with product release appeared to occur with the inhibition reaction, which explained this degree of clavulanic acid turnover. The stoichiometry of the interaction with Klebsiella β-lactamase was not examined. The penicillinase from Proteus mirabilis C889 was rapidly inhibited by low concentrations of clavulanic acid. The major product was a moderately stable complex (t½=40min at pH7.3 and 37°C); the proportion of the enzyme that was irreversibly inactivated was small. The cephalosporinase from Enterobacter cloacae P99 had low affinity for the inhibitor and only reacted with high concentrations of clavulanic acid (k=4.0m−1·s−1) to produce a relatively stable complex (t½=180min at pH7.3 and 37°C). No irreversible inactivation of this enzyme was detected. The rates of decay of the clavulanate–enzyme complexes produced in reactions with Proteus and Enterobacter enzymes were markedly increased at acid pH.

The Effect of Urea on Aggregation and Incubation Resistance of Human Platelets

1969 ◽  
Vol 21 (03) ◽  
pp. 403-408
Author(s):  
H Reuter ◽  
H Linker
Keyword(s):  
Platelet Rich Plasma ◽  
Divalent Cations ◽  
Human Platelets ◽  
Low Concentrations ◽  
Edta Plasma ◽  
Presence And Absence ◽  
High Concentrations ◽  
Induced Aggregation

SummaryInvestigations have been carried out to study the effect of urea on aggregation and incubation resistance of human platelets. Urea in high concentrations inhibits the Ca++-induced aggregation in platelet-rich EDTA-plasma while at low concentrations an increased aggregation takes place. Incubation of platelet-rich plasma at 37° C in the absence of divalent cations was performed in the presence and absence of 0.1 M urea. The temperature-induced percentage inhibition of aggregation was found to be significantly lower in the presence of urea.

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