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

Two groups of specifically presensitized Macaca speciosa monkeys received renal allografts via anastomosis to an indwelling arteriovenous (A-V) shunt. One group was pretreated with heparin (2 mg/kg) intravenously and the other was also treated with constant heparin infusion (1 mg/kg/hr) directly into the renal artery. These studies were performed to evaluate the effects of heparin within the kidney on total and compartmental blood flow, complement (C3) levels, sequestration of formed elements, and activation of the coagulation, fibrinolytic, and kinin-forming systems during the initial 3 hours of hyperacute rejection. The results are compared with those previously reported in unmodified control allografts. Heparin prolonged blood clotting time to infinity, markedly prolonged total renal venous blood flow, and normalized compartmental distribution in both groups despite antibody deposition similar to that in controls. With heparin pretreatment only, initial morphologic injury was much reduced but then progressed rapidly. Marked initial cortical cyanosis with mottling appeared to change constantly and was associated with fluctuations in renal turgor, total blood flow, and sequestration of formed elements, all of which suggested repetitive local cortical arterial spasm and incremental destruction of the grafts. Activation of coagulation Factors II and XII was also revealed and marked net Factor VIII activity was observed in the venous effluent. The latter reflects either formation and release of this factor by the injured kidney, or provides in vivo documentation of the "hyperactivation" of Factor VIII by thrombin known to occur in vitro. The addition of intrarenal artery heparin infusion resulted in greater improvement in early total blood flow rates and more uniformly progressive cyanosis and loss of turgor, but the diffuse initial morphologic injury suggested more uniform perfusion of injured areas. Intrarenal consumption of C3 and sequestration of formed elements was similar to that in controls. Paradoxically, prompt activation and consumption of all coagulation factors, plasminogen, and prekallikrein were observed, but formed fibrin was sparse. The exess amount of Factor XIIa present during heparin blockade may have been diverted to production of plasminogen activator and kallikrein formation. The enormous numbers of neutrophils observed within vessels of grafts which showed the greatest kallikrein activation provide the probable in vivo demonstration of the chemotactic properties of kallikrein noted by others in vitro. Heparin-induced platelet aggregation may have played an important role in the failure of these grafts. These studies elucidate the intrarenal effects of heparin during hyperacute rejection and again suggest that vasoconstriction is the most important early determinant of graft failure, as blood flow appeared unrelated to the degree of vascular injury and apparent obstruction. Also, heparin may exer a beneficial effect on blood flow by other than its known action on coagulation.
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PMID:Hyperacute renal allograft rejection in the primate. Intrarenal effects of heparin and associated net release of factor VIII activity and kallikrein activation. 109 75

The authors investigated blood coagulation activity in patients who underwent microsurgery. Hemostatic parameters were measured in 9 patients (10 operations) who were undergoing free tissue transfers. These parameters included prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinopeptide A (FPA), prothrombin fragment 1 + 2 (F1 + 2), and thrombin-antithrombin complex (TAT). The flap totally necrosed owing to vasospasm in 1 patient with osteomyelitis of the heel, and the FPA, F1 + 2, and TAT values significantly increased. Reexploration was required because of flap cyanosis in 1 patient with a hemangioma on the wrist, and the F1 + 2 and TAT values increased during the salvage procedure. These molecular markers could be important in indicating hypercoagulable state sensitivity, and they serve as a warning of possible vascular compromise to a surgeon.
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PMID:Blood coagulation activity during microsurgery. 946 97

We have investigated hemostatic parameters including platelet activation in 56 pediatric patients with or without cyanosis undergoing cardiopulmonary bypass (CPB) and cardiac surgery to repair congenital defects. Patients were participants in a study assessing the effects of tranexamic acid on surgery-related blood loss. Parameters monitored included blood loss, prothrombin F1.2, thrombin-antithrombin complexes, t-PA, PAI-1, plasminogen, fibrin D-dimer, and plasma factor XIII. Additionally, flow cytometry monitored platelet degranulation (P-selectin or CD63), as well as surface-bound fibrinogen, von Willebrand factor and factor XIIIa. Cyanotic patients had evidence of supranormal coagulation activation as both fibrin D-dimer and PAI-1 levels were elevated prior to surgery. While the extent of expression of P-selectin or CD63 was not informative, platelet-associated factor XIIIa was elevated in cyanotic patients at baseline. In both patient groups, CPB altered platelet activation state and coagulation status irrespective of the use of tranexamic acid.
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PMID:Hemostatic parameters and platelet activation marker expression in cyanotic and acyanotic pediatric patients undergoing cardiac surgery in the presence of tranexamic acid. 1066 55

Protein C is a plasmatic protein that is synthesized by the liver with the help of vitamin K. It regulates thrombin formation and consequently prevents thrombosis. We present a case of a newborn male with change in the color of the right foot index finger who after 4 h showed cyanosis that reached malleolus level. Upon admission we observed generalized pallor, tachycardia and a necrotic lesion in the rightfoot. We suspected a septic process and thus administered cefotaxime, vancomycin and heparin. Platelet levels were 70,000 mm3, thromboplastin 16/12 sec., partial thromboplastin 5829 sec. PCfunctionality 20% and protein S 100%. Even though the patient evolvedfavourably and showed partial recovery, an intratuberous amputation was needed. One year later a prosthesis was fitted. We need to carry out studies that support the use of PC monoclonal antibodies in order to offer better baseline treatment to patients with PC congenital deficiency and improve their quality of live.
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PMID:[Protein C congenital deficiency. A case report]. 1602 90

Cerebral infarction is a common cause of seizures in neonates with a prevalence of I in 4000 live births. We report two neonates with different presentations due to cerebral infarction and discuss their etiological and neuroradiological findings in this case report. The initial signs were cyanosis and convulsion. In case 1, tonic convulsion, eye deviation, while case 2 had additionally poor sucking and dehydration as a risk factor. Their evaluation for hereditary causes of thrombosis was unremarkable. With these 2 cases, it is emphasized that neonatal cerebal infarction may be a cause of neonatal convulsion. Hence, neonates with cerebral infarction should be evaluated for hereditary conditions like protein C and S deficiency, anti-thrombin III deficiency, Factor V leiden mutation, prothrombin gene mutation and homocystinuria.
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PMID:Cerebral infarctions manifesting as neonatal seizure. 1790 13

Obstetric crisis includes hemorrhagic shock, embolisms and difficult airway. Life will be rapidly threatened with disseminated intravascular coagulation, multiple organ failure or systemic inflammatory response syndrome in these crises. In the face of the crisis, repeated evaluation of parturients and differential diagnosis are necessary along with fetal heart monitoring. For evaluation of bleeding, one should notice that the visual estimation of vaginal bleeding does not reflect the extent of intravascular volume deficit. Treatments for hemorrhagic shock include fluid replacement, blood transfusion as well as fresh frozen plasma, platelet, anticoagulants, anti-thrombin III, and protease inhibitors. When bleeding is still uncontrollable, arterial embolization or hysterectomy will be considered. Embolic disorders are another cause of maternal mortality. The signs and symptoms are all similar (dyspnea, cyanosis and sudden cardiovascular collapse). Strategies against the embolism will be basically symptomatic therapy. The physiological change with pregnancy results in the need of careful pre-anesthetic airway evaluation for parturients. A difficult or failed intubation drill is also extremely important. Recently, laryngeal mask airway has been successfully used in these parturients. During resuscitation of a pregnant woman, left uterine displacement is essential. For a patient who has not responded after 4 to 5 minutes of ACLS, immediate cesarean delivery should be considered.
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PMID:[Crisis management during obstetric surgery]. 1946 96

Cardiopulmonary bypass (CPB) creates a pro-coagulant state by causing platelet activation and inflammation leading to thrombin generation and platelet dysfunction. It is associated with severe derangements in normal homeostasis resulting in both thrombotic and hemorrhagic complications. This derangement is greater in children with congenital heart disease than in adults because of the immaturity of the coagulation system, hemodilution of coagulation factors, hyperreactive platelets, and in some patients, physiologic changes associated with cyanosis. During CPB, an appropriate amount of heparin is given with the goal of minimizing the risk of thrombosis and platelet activation and at the same time reducing the risk of bleeding from over anticoagulation. In young children, this balance is more difficult to achieve because of inherent characteristics of the hemostatic system in these patients. Historically, protocols for heparin dosing and monitoring in children have been adapted from adult protocols without re-validation for children. Extreme hemodilution of coagulation factors and platelets in young children affects the accuracy of anticoagulation monitoring in children. The activated clotting time does not correlate with plasma levels of heparin. In addition, recent studies suggest that children need larger doses of heparin than adults, because they have lower antithrombin levels, and they metabolize heparin more rapidly. Preliminary studies demonstrated that the use of individualized heparin and protamine monitoring and management in children is associated with reduced platelet activation and dysfunction and improved clinical outcomes. However, this review article clearly establishes that further studies are necessary to obtain evidence-based protocols for the proper management of anticoagulation of children undergoing cardiopulmonary bypass.
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PMID:Management and monitoring of anticoagulation for children undergoing cardiopulmonary bypass in cardiac surgery. 2043 87