Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.5 (thrombin)
 33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The anaphylactic response to an i.v. injection of antigen into rabbits making only IgE antibody against the antigen was shown to be preceded by a disappearance of the metachromatic staining properties of the circulating basophils and was accompanied by marked but transient thrombocytopenia. The platelets which returned to the circulation 1 hr after the anaphylaxis were shown to be unresponsive to the secretion-inducing activity of basophil-derived platelet-activating factor (PAF) when compared with platelets examined before antigen challenge. By contrast, platelet responsiveness to other stimuli such as collagen, thrombin, and C3b was unchanged. The specific desensitization to PAF provides strong evidence for the action of this mediator on platelets in vivo during IgE-mediated anaphylaxis and provides a useful tool for detecting the effects of particular cell activators in inflammatory reactions.
 ...
PMID:Basophil-derived platelet-activating factor (PAF) as an in vivo mediator of acute allergic reactions: demonstration of specific desensitization of platelets to PAF during IgE-induced anaphylaxis in the rabbit. 91 94

In active anaphylactic shock of rats pretreated with Bordetella pertussis vaccine, both plasma thrombin clotting time and the amount of antigenically active fibrinogen degradation products in the serum were increased. The formation of clottable fibrinogen fragments was shown by SDS polyacrylamide gel electrophoresis of thrombin-induced clots. When plasma of rats pretreated with 125I rat fibrinogen and then subjected to anaphylaxis was submitted to SDS polyacrylamide gel electrophoresis, fibrinogen-split products were also detected. Fibrinogen degradation results from the proteolytic effect of an activated fibrinolytic enzyme.
 ...
PMID:Evidence of fibrinogen degradation in rat anaphylaxis. 115 26

In the PRP of anaphylactic rats, ADP, collagen and thrombin induced platelet aggregation was considerably reduced. Reduced aggregability could be transferred to normal platelets by suspending them in the PPP of anaphylactic animals and the impaired aggregation of platelets from animals undergoing anaphylaxis could be restored by exchanging their plasma for that of normal controls. Ellagic acid, a known activator of factor XII, produced similar alterations as obtained in anaphylactic shcok. It is suggested that the inhibition of platelet aggregation is due to the anaphylactic activation of factor XII and this mechanism may be of importance in rat anaphylaxis.
 ...
PMID:Reduced aggregability of platelets in rat anaphylaxis. 126 97

Tryptase from human mast cells has been shown (in vitro) to catalyze the destruction of fibrinogen and high-molecular-weight kininogen as well as the activation of C3a and collagenase. Although large amounts of tryptase are released in tissues by degranulating mast cells and levels as high as 1000 ng/ml have been measured in the circulation following systemic anaphylaxis, no specific physiologic inhibitor has yet been found for the protease. The current work tests several more inhibitors for their effects on tryptase and examines any effect of tryptase on these inhibitors. First, antileukoprotease and low-molecular-weight elastase inhibitor from human lung and hirudin and antithrombin III had no effect on tryptase activity in vitro. Second, the possibility that tryptase, being insensitive to the effects of inhibitors, might instead destroy them was also considered. Tryptase failed to cleave and inactivate antileukoprotease, low-molecular-weight elastase inhibitor, alpha 1 protease inhibitor, alpha 2 macroglobulin, and antithrombin III. Third, based on the knowledge that tryptase stability is regulated by its interaction with heparin, antithrombin III was used as a model heparin-binding protein to demonstrate that a protein competitor for heparin-binding sites, presumably by displacement of tryptase, destabilizes this enzyme. Conversely, tryptase, in excess, blocked the binding of antithrombin III to heparin, thereby attenuating the heparin-mediated inhibition of thrombin by antithrombin III.
 ...
PMID:Interactions of human mast cell tryptase with biological protease inhibitors. 168 95

A thrombin-like proteinase (THROLP) was detected colorimetrically as the main proteolytic activity (PROA) in the lavage fluid some minutes after antigen challenge of rats for passive peritoneal anaphylaxis (PPA) reaction. THROLP is equivalent to histamine (H) as parameter for the early phase of PPA: both increased significantly after 6 min, but decreased to prechallenge levels 20 min after challenge. H was released from serosal mast cells, in contrast THROLP originates predominantly from plasma leakage and activation of the clotting reaction in PPA. These findings underline the importance of PROA in the sequence of allergic reactions.
 ...
PMID:Time course of immediate release and relationships between thrombin-like proteinase, other proteinases, histamine, protein and dye extravasation in rat passive peritoneal anaphylaxis. 171 90

Topically applied thrombin was known to be effective in hemostasis of local bleeding, but complications of shock, anaphylaxis or disseminated intravascular coagulation (DIC) have been reported recently in rare cases. In this experiment, the possibility of DIC was examined by intraperitoneal injection of topical thrombin (Parke-Davis) to rabbits with liver cirrhosis or acute liver damages induced by CCl4. No significant changes in the coagulation parameters were found in the groups of liver cirrhosis or the untreated control, but the injection of thrombin induced decreases of platelet count and fibrinogen and prolongation of prothrombin time and partial thromboplastin time in the groups of acute liver damages, 24 or 48 hr after CCl4 injection. When the "junk" prepared from the topical thrombin was injected to the 48 hr-damage group, no change was noted in these parameters. It was concluded that DIC could be induced by the intraperitoneal injection of topical thrombin only in cases of acute liver damages, where the increased permeability of peritoneum was postulated. However, such an immediate or marked change in coagulation was not found in our experiment as encountered in the clinical cases, which suggested the involvement of the anaphylactic reaction to the topical application of thrombin in the development of DIC in these clinical cases.
 ...
PMID:[Effect of intraperitoneal injection of topical thrombin on the coagulation and fibrinolysis of rabbits with experimental liver damages]. 398 69

Sixteen atopic patients with anaphylaxis to food, eczema, asthma and/or rhinitis were investigated for in vitro reactivity of their leukocytes and platelets to various stimuli. Leukocytes from two patients with anaphylaxis to foods had very high spontaneous release of histamine. Compared to non-atopic volunteers without respiratory disease, leukocytes from the other atopic patients showed increased histamine release after stimulation with methacholine in concentrations between 10(-2) and 10(-6) M. Histamine release induced by anti-IgE or anti-kappa chain serum was slightly decreased in atopics compared to controls, and was significantly decreased at low concentrations of anti-IgE (p less than 0.05). There was no significant difference of means for histamine release induced by the calcium ionophore A-23815. The uptake of 3H serotonin from platelet-rich plasma of atopic patients appeared to occur more slowly than in non-atopics. Serotonin release from washed platelets after stimulation with aggregated IgG was significantly lower in the atopic group (p less than 0.01). There was no significant difference in serotonin release induced by thrombin, epinephrine, ionophore or methacholine. Alterations in releasability of mediator containing cells to immunologic and non-immunologic stimuli may play a role in the expression of atopic disease.
 ...
PMID:In vitro releasability of histamine and serotonin: studies of atopic patients. 616 59

FUT-175 (6 amidino-2-naphthyl-4-guanidino benzoate-dimethanesulfonate), a new synthetic protease inhibitor, inhibits the enzyme activities of various proteases, such as Clr, C1 esterase, thrombin, kallikrein, plasmin and trypsin. FUT-175 strongly inhibited complement-medicated hemolysis via the classical and alternative pathways. The effects of FUT-175 on various immunological reactions in vivo were studied. The minimal effective dose of FUT-175 in systemic Forssman shock in guinea pigs was 6.25 mg/kg i.p. and 25 mg/kg p.o. In passive Arthus reactions in rats, the effective dose was 25 mg/kg i.p. and 250 mg/kg p.o. FUT-175 also inhibited other immunological reactions, such as passive cutaneous anaphylaxis and delayed hypersensitivity. Furthermore, at a dose of 25 mg/kg i.p. it strongly protected mice from death in endotoxin shock.
 ...
PMID:Inhibition of various immunological reactions in vivo by a new synthetic complement inhibitor. 621 61

Profuse hemostatic defects were demonstrable 14 hr after wasp sting anaphylaxis. The patient's plasma contained an agent or agents that interfered with the action of thrombin, impeding the release of fibrinopeptide A from fibrinogen and the hydrolysis of the synthetic amide H-D-prolyl-L-phenylalanyl-L-arginine p-nitroanilide. This inhibitor could not be equated with known plasma inhibitors of thrombin nor with heparin. Additionally, the titers of nearly all other known clotting factors were reduced as compared to levels obtained after the patient's recovery. Of particular interest were profound reductions in the titers of proaccelerin (factor V) and high molecular weight kininogen. A normal titer of Hageman factor (factor XII) argued against participation of contact-activated mechanisms in the induction of the multiple abnormalities observed. Attempts to demonstrate the release of procoagulant or anticoagulant substances from the patient's convalescent blood, plasma, serum, or leukocytes upon challenge with wasp venom were unsuccessful. The observations reported confirm and extend information concerning hemostatic abnormalities in anaphylaxis, and point out the need to examine further this puzzling association.
 ...
PMID:Wasp sting anaphylaxis. 633 52

Thromboxane A2 (rabbit aorta-contracting substance) is a proaggregatory vasoconstrictive, oxygenated metabolite of arachidonic acid which was originally discovered in guinea pig lung perfusates during antigen-induced anaphylaxis. The specific stimuli which activate synthesis and the cellular source in the lung remain undefined. In order to study pulmonary thromboxane A2 (TXA2) synthesis, a cultured lung cell model has been used. Monolayer cultures of human diploid embryonic lung fibroblast (WI-38) metabolized exogenously supplied [14C]arachidonic acid to TXA2 as well as prostaglandin E2. Both were unequivocally identified by gas chromatography/mass spectrometry. Cellular phospholipids were labeled by preincubating cultures overnight with [14C]arachidonic acid. Release of thromboxane A2 into the culture fluid from these prelabeled cultures was stimulated by two phospholipase activating agents, mellitin and the calcium ionophore A23187. The lung cells also released TXA2 and prostaglandin in a dose-dependent fashion when treated with thrombin but not when exposed to trypsin. Bradykinin, an anaphylactic mediator in vivo, was a potent TXA2 releasing agent in this in vitro system whereas histamine was inactive. In addition, anaphylactic shock perfusates from guinea pig lung were shown to contain a factor (other than bradykinin) which activates fibroblasts TXA2 synthesis in these cultured lung cells. These experiments indicate that the lung fibroblast is probably a source of pulmonary thromboxane in vivo and that the cultured lung cell system described here is a useful model for defining the complex interactions of mediators of anaphylaxis and asthma.
 ...
PMID:Lipid metabolism in cultured cells. Activators of endogenous thromboxane A2 synthesis in cultured lung fibroblasts. 680 Oct 37


1 2 3 Next >>