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Biomedical subjects

G L Reed

Publications and source records attributed to G L Reed.

10 recordsLinked to original sources
PubMed1992

Platelet factor XIII increases the fibrinolytic resistance of platelet-rich clots by accelerating the crosslinking of alpha 2-antiplasmin to fibrin.

Platelet clots resist fibrinolysis by plasminogen activators. We hypothesized that platelet factor XIII may enhance the fibrinolytic resistance of platelet-rich clots by catalyzing the crosslinking of alpha 2-antiplasmin (alpha 2AP) to fibrin. Analysis of plasma clot structure by polyacrylamide gel electrophoresis and immunoblotting revealed accelerated alpha 2AP-fibrin crosslinking in platelet-rich compared with platelet-depleted plasma clots. A similar study of clots formed with purified fibrinogen (depleted of factor XIII activity), isolated platelets, and specific factor XIII inhibitors indicated that this accelerated crosslinking was due to the catalytic activity of platelet factor XIII. Moreover, when washed platelets were aggregated by thrombin, there was evidence of platelet factor XIII-mediated crosslinking between platelet alpha 2AP and platelet fibrin(ogen). Specific inhibition (by a monoclonal antibody) of the alpha 2AP associated with washed platelet aggregates accelerated the fibrinolysis of the platelet aggregate. Thus in platelet-rich plasma clots, and in thrombin-induced platelet aggregates, platelet factor XIII actively formed alpha 2AP-fibrin crosslinks, which appeared to enhance the resistance of platelet-rich clots to fibrinolysis.

Blood Coagulation Factors↗
PubMed1992

Generation of species-specific, rat monoclonal antibodies that bind to the kappa chain of mouse immunoglobulin.

Large numbers of mouse monoclonal antibodies (MAbs) with exquisite binding specificities have become available. However the study of these primary antibodies in biological fluids by second, anti-mouse antibody techniques, has been confounded by the large quantity of other animal immunoglobulin which is often present in these fluids. To overcome this problem, we have derived high affinity rat MAbs which bind specifically to the antigen binding fragments (Fab) of mouse antibody and display minimal or no crossreactivity with human or rabbit immunoglobulin at the concentrations which are usually found in plasma. Equilibrium binding studies demonstrated that these antibodies had binding affinity constants for mouse Fab that ranged from 4.3 x 10(8) to 4.1 x 10(9) M-1. All of these rat MAbs bound to the kappa chain of mouse immunoglobulin, though competition binding studies amongst these MAbs indicated that they probably recognized three different epitopes. Because of their specificity and affinity, these rat anti-mouse kappa MAbs may be useful in a wide variety of experimental biological systems both in vitro and in vivo.

Animals↗
PubMed1991

Inhibition of factor XIII activation by an anti-peptide monoclonal antibody.

As the final enzyme in the coagulation cascade, activated fibrin stabilizing factor or factor XIII catalyzes the intermolecular cross-linking of fibrin chains. To study this enzyme in plasma, we derived a monoclonal antibody (MAb 309) against a peptide sequence (NH2-G-V-N-L-Q-E-F-C-COOH) in the thrombin activation site of factor XIII. Radioimmunoassays indicate that MAb 309 binds specifically to both platelet and plasma factor XIII. Peptide inhibition studies demonstrate that the MAb binds equally well to the factor XIII (FXIII) zymogen and the active form of FXIII (FXIIIa). In immunoblots of whole platelet lysates, MAb 309 binds only to FXIII and does not cross-react with other proteins. In saturation binding studies, the antibody shows a binding avidity of (1.75 +/- 0.35) x 10(9) M-1. MAb 309 also inhibited 99% of apparent FXIIIa activity in a standard transglutaminase assay. SDS-PAGE analysis of fibrin clots showed that MAb 309 inhibited fibrin gamma-gamma cross-linking. Moreover, MAb 309 accelerated the lysis of plasma clots, consistent with inhibition of fibrin-fibrin and fibrin-alpha 2-antiplasmin cross-linking. Immunoblotting experiments revealed that MAb 309 affected apparent FXIIIa activity by inhibiting the thrombin activation of the FXIII zymogen. In addition to its utility as a specific probe for the FXIII a-subunit, the strategy used to obtain MAb 309 may be used to generate MAbs that inhibit the activation of other coagulation factor zymogens.

Amino Acid Sequence↗
PubMed1990

Synergistic fibrinolysis: combined effects of plasminogen activators and an antibody that inhibits alpha 2-antiplasmin.

To improve the efficacy of plasminogen activators, we produced a monoclonal antibody (RWR) that inhibits human alpha 2-antiplasmin (alpha 2AP). In addition to inhibiting alpha 2AP in plasma, RWR binds to and inhibits fibrin cross-linked alpha 2AP and reproduces the "spontaneous" clot lysis that is the hallmark of human alpha 2AP deficiency. By inhibiting the inactivation of plasmin by alpha 2AP, RWR interacts synergistically with plasminogen activators to increase the potency (for 50% clot lysis) of urokinase by 80-fold, tissue plasminogen activator by 27-fold, and streptokinase by 20-fold. Yet, for a given amount of fibrinolysis, the combination of RWR and lower doses of plasminogen activator leads to less fibrinogen consumption than is obtained with higher, equipotent doses of plasminogen activator alone. These results suggest a strategy for increasing the efficacy of plasminogen activators. More generally, this approach to amplifying enzymatic activity by immunoneutralizing an inhibitor may be useful in other biologic processes that are rigidly governed by inhibitors.

Antibodies, Monoclonal↗
PubMed1990

Inhibition of clot-bound alpha 2-antiplasmin enhances in vivo thrombolysis.

Recent experiments in vitro have shown that inhibition of human alpha 2-antiplasmin by a monoclonal antibody (MAb RWR) markedly enhances clot lysis by plasminogen activators. To extend these studies in vivo, we tested whether inhibition of clot or fibrin-bound alpha 2-antiplasmin by MAb RWR could enhance the lysis of a human clot by tissue-type plasminogen activator (t-PA) in a rabbit jugular vein thrombosis model. Compared with a saline placebo or a control antibody, MAb RWR significantly increased thrombolysis by endogenous plasminogen activator in rabbits to which no t-PA was administered (p less than 0.05). In rabbits that received t-PA, the combination of MAb RWR and t-PA caused significantly greater thrombolysis than equivalent doses of t-PA alone (p less than 0.05). However, compared with equipotent doses of t-PA alone, the combination of MAb RWR and t-PA did not increase the nonspecific consumption of fibrinogen. These experiments suggest that the combination of an alpha 2-antiplasmin inhibitor and a plasminogen activator could be a more potent thrombolytic strategy.

Animals↗
PubMed1988

Stroke following coronary-artery bypass surgery. A case-control estimate of the risk from carotid bruits.

The causes of stroke following coronary-artery bypass surgery are largely unknown. To determine whether carotid bruits increase the risk of these events, we compared 54 patients with postoperative stroke or transient ischemic attacks with 54 randomly selected control patients. Both groups were drawn from 5915 consecutive patients who had coronary bypass surgery at our hospital from 1970 to 1984. Carotid bruits were noted preoperatively in 13 patients with postoperative stroke and in 4 control patients. Case-control analysis showed that the presence of carotid bruits increased the risk of stroke or transient ischemic attacks by 3.9-fold (95 percent confidence interval, 1.2 to 12.8; P less than 0.05). This increased risk remained essentially unchanged after adjustment for potentially confounding variables in a multiple logistic regression analysis. Other factors associated with a significantly increased risk (P less than 0.05) of these neurologic deficits were a history of stroke or transient ischemic attack (odds ratio, 6.0; 95 percent confidence interval, 1.6 to 22.1), a history of congestive heart failure (odds ratio, 5.3; confidence interval, 1.6 to 17.0), mitral regurgitation (odds ratio, 4.3; confidence interval, 1.4 to 12.9), postoperative atrial fibrillation (odds ratio, 3.0; confidence interval, 1.4 to 6.7), a cardiopulmonary-bypass pump time of more than two hours (odds ratio, 2.7; confidence interval, 1.1 to 6.7), and a previous myocardial infarction (odds ratio, 2.3; confidence interval, 1.1 to 5.1). We conclude that the presence of carotid bruits increases the risk of stroke after coronary-artery bypass surgery. However, the absolute magnitude of this risk, 2.9 percent, is small and comparable to the reported risk of stroke from carotid endarterectomy.

Atrial Fibrillation↗
PubMed1975

Pagano-Levin Candida test medium: evaluation using vaginal samples.

Since 1958 pagano-Levin medium (PLM) has been used as an aid in the identification of Candida albicans. However, no statistical analysis of its effectiveness based on large number of random human specimens has been reported. The present study compared PLM (now called Candida test) with Sabouraud's plus antimicrobials and Littman's ox-gall agar without antimicrobials. Of 500 random vaginal samples 24.8 were true positives, 71.9% were true negatives, 2.2% were false positives, and 1.2% were false negatives on PLM. If only samples identified as C. albicans were considered, 95.4% were true positives and 4.6% were false negatives. PLM did not inhibit C. albicans from the vagina. No one medium was found superior to the others for the purpose of isolating and identifying C. albicans. Of the five strains of C. parapsilosis, the only other Candida species isolated, all the samples grew on PLM but most were inhibited on Sabouraud's medium plus antimicrobials.

Candida↗