PubMed Health⌕ Search

Biomedical subjects

D L Aronson

Publications and source records attributed to D L Aronson.

At least 19 recordsLinked to original sources
PubMed1992

Platelet-dependent thrombin generation after in vitro fibrinolytic treatment.

BACKGROUND: Fibrinolytic therapy is associated with frequent rethrombosis. There is evidence of both increased coagulation and platelet activation. METHODS AND RESULTS: Platelet-rich plasma (PRP) or washed platelets were incubated with the fibrinolytic agents urokinase, recombinant tissue-type plasminogen activator (rt-PA), or plasmin at concentrations consistent with those in the plasma of patients treated for myocardial infarction. All of the fibrinolytic agents induced a more rapid generation of thrombin and decreased the clotting times of non-contact-activated PRP than in untreated PRP. This effect was not blocked by the inclusion of thrombin inhibitors during the fibrinolytic treatment. Washed platelets derived from rt-PA-treated PRP induced more rapid thrombin generation when resuspended in untreated plasma or treated plasma. Washed platelets were treated with plasmin, rt-PA, and urokinase and added to platelet-poor plasma. Platelets treated with either plasmin or rt-PA increased the ability of washed platelets to support thrombin generation, but urokinase was without significant effect. CONCLUSIONS: These results indicate not only that plasmin can cause increased platelet support of prothrombin activation but also that rt-PA in the absence of plasminogen can have a direct effect on the platelet, which increases thrombin generation.

Blood Platelets↗
PubMed1986

Turnover of human tissue plasminogen activator (tPA) in rabbits.

The turnover of purified tissue plasminogen activator (tPA) from two different manufacturers was compared in rabbits. The first was melanoma derived one-chain tPA and the second was recombinant two-chain tPA. No differences were noted between the two products. A biphasic disappearance curve was observed for the protein (125Iodine labelled). The first phase was extremely rapid with a T1/2 of 0.59-0.89 min; the secondary phase had a T1/2 of 10-12 min. tPA accumulated rapidly in the liver (44% at twenty min) and appeared to be degraded as demonstrated by the increase in plasma of low molecular weight material which was also TCA soluble. Fractionation of purified recombinant two-chain tPA on a Dupont GF-250 column yielded two peaks of protein (Peak 1 and Peak 2) and the turnover of each in rabbits was compared.

Animals↗
PubMed1979

Physical studies on isolated human prothrombin fragment-2. Comparisons with human prothrombin fragment-1.

Variation of pH strongly affects the fluorescence intensity of human prothrombin fragment-1 in a manner suggesting contributions from a number of protropic equilibria including groups with apparent pKa values near 3.0. These results suggest a structural role for pK1a of gamma-carboxyglutamic acid noieties. Added calcium ions (9 mM calcium chloride) quench the fluorescence titration curve uniformly above pH 4. Below pH 4, however, the titration curve in the presence of calcium ions suggests that calcium-ion-dependent processes leading to fluorescence quenching are pH-dependent. Upon back titration of human fragment-1, from pH 9, hysteresis is observed. Human prothrombin fragment-2 fluorescence titration curves are relatively broad at low pH suggesting the titration of normal carboxyl groups. The titration curves of fragment-2 are not affected by the presence of calcium ions, and hysteresis occurs upon back titration from low pH values. Circular dichroism (CD) Cotton effects appear at 232 nm and 280 nm and a trough appears at 203 nm in the CD spectrum of human prothrombin fragment-2. The Cotton effects in the region from 230 nm to 300 nm are sensitive to pH, ellipticity values at 232 nm increasing from approximately 300 at pH 2.5 to 1300 (degree-cm/decimole) at neutral pH and finally become negative at high pH values. In contrast to fragment-1, at neutral pH the fragment-2 Cotton effect at 232 nm is insensitive to the presence of 8 mM calcium chloride.

Calcium↗
PubMed1979

Factor IX complex.

Explore the source record for details and available documents.

Disseminated Intravascular Coagulation↗
PubMed1977

Generation of the combined prothrombin activation peptide (F1-2) during the clotting of blood and plasma.

We have investigated the pathway of prothrombin activation in blood and plasma. By means of a rapid purification procedure involving chromatography on DEAE-cellulose and hydroxyapatite, we demonstrated that the major prothrombin fragment in serum is that representing the amino-terminal half of prothrombin (i.e. F1-2). The F1-2 isolated was characterized by its size, amino acid and antigenic compositions, amino-terminal residue, and the peptides (designated F1 and F2, respectively) it yielded upon hydrolysis by thrombin. Measurements by the isotope dilution technique showed that F1-2 could account for the fate of at least 90% of the prothrombin originally present in plasma. By contrast, the serum concentration of the fragment representing the amino-terminal third of prothrombin (viz. F1) was less than 10% that of F1-2. These results demonstrated that the major route of prothrombin conversion in blood or plasma involves the removal of the combined activation fragment (F1-2) as a single peptide.

Amino Acid Sequence↗
PubMed1976

The activation of human factor X in sodium citrate: the role of factor VII.

Human factor X was purified by several different procedures yielding products which had varying amounts of factor VII and factor IX. Treatment with CHCl3 during the fractionation of the factor X removed 95% of the factor VII and factor IX activity and the resulting factor X activated more slowly when incubated in 25% sodium citrate. Removal of residual factor VII by DEAE cellulose chromatography yielded a factor X which activated still more slowly and less completely. When the factor VII, removed by chromatography, was added to the chromatographed factor X, the ability to be activated in 25% sodium citrate was restored. Confirmatory evidence for the role of factor VII in this reaction was the inhibition of the conversion of the factor X by both DFP and SBTI.

Citrates↗
PubMed1976

Comparison of the actions of thrombin and the thrombin-like venom enzymes ancrod and batroxobin.

Thrombin acts on several coagulant proteins to produce products with physiologic, pharmacologic and pathologic potential. The most sensitive thrombin substrate seems to be factor VIII. Some thrombin dependent reactions studied in vitro and proposed as control reactions seem too insensitive to the action of thrombin to be of in vivo significance. The only enzymic reaction the thrombin-like venom enzymes, Ancrod and Batroxobin, have in common with thrombin is the removal of fibrinopeptide A.

Ancrod↗