Intraperitoneal administration of activated protein C prevents postsurgical adhesion band formation.

Postsurgical peritoneal adhesion bands are the most important causes of intestinal obstruction, pelvic pain, and female infertility. In this study, we used a mouse model of adhesion and compared the protective effect of activated protein C (APC) to that of the Food and Drug Administration-approved antiadhesion agent, sodium hyaluronate/carboxymethylcellulose (Seprafilm) by intraperitoneal administration of either APC or Seprafilm to experimental animals. Pathological adhesion bands were graded on day 7, and peritoneal fluid concentrations of tissue plasminogen activator (tPA), d-dimer, thrombin-antithrombin complex, and cytokines (IL-1ß, IL-6, interferon-γ, tumor necrosis factor-α, transforming growth factor-ß1) were evaluated. Inflammation scores were also measured based on histologic data obtained from peritoneal tissues. Relative to Seprafilm, intraperitoneal administration of human APC led to significantly higher reduction of postsurgical adhesion bands. Moreover, a markedly lower inflammation score was obtained in the adhesive tissues of the APC-treated group, which correlated with significantly reduced peritoneal concentrations of proinflammatory cytokines and an elevated tPA level. Further studies using variants of human APC with or without protease-activated receptor 1 (PAR1) signaling function and mutant mice deficient for either endothelial protein C receptor (EPCR) or PAR1 revealed that the EPCR-dependent signaling activity of APC is primarily responsible for its protective activity in this model. These results suggest APC has therapeutic potential for preventing postsurgical adhesion bands.

[Pharmacological therapies for ARDS].

Acute respiratory distress syndrome (ARDS) is a noncardiogenic pulmonary edema resulting from increased capillary permeability. Numerous pharmacologic therapies have been studied for prevention and treatment of ARDS. Although several pharmacological therapies could improve patient's respiratory function, there have been no controlled studies which clearly demonstrated the clinical benefit for ARDS-related mortality. The role of corticosteroids in ARDS remains controversial. Available evidence is against early administration of high-dose corticosteroids (methylprednisolon 120 mg x kg-1 x day - 1). In contrast, low-dose corticosteroid therapy (methylprednisolon 0.5-2.5mgg kg-1 xday-1)remains controversial. With regard to sivelestat sodium, a specific inhibitor of neutrophil elastase, although the effectiveness in decreasing mortality was not clarified, increases in lung oxygenation and ventilator-free days have consistently been revealed. Other probable pharmacologic therapies for ARDS include continuous infusion of cisatracurium. In conclusion, there are not established drugs for ARDS, and further studies are necessary to reveal the clinical effectiveness of the above mentioned and novel pharmacologic therapies.

[Varicella-associated purpura fulminans and deep vein thrombosis: a pediatric case report]. / Purpura fulminans post-varicelleux et thrombose veineuse : à propos d'un cas pédiatrique.

Purpura fulminans (PF) and deep vein thrombosis are rare complications secondary to chicken pox disease. The presence of antibodies reflects an ongoing immunological process and requires specialized management. The present study reports a 4-year-old boy with no medical history who presented with purpura on the legs 10 days after chicken pox eruption. Laboratory tests showed a disseminated intravascular coagulation associated with low plasma protein C and S activities, and the presence of anti-protein S antibodies. A replacement therapy with protein C infusions and fresh frozen plasma was prescribed. The patient also underwent regular sessions of hyperbaric oxygen followed by the surgery. Fourteen days after the beginning of the purpuric lesions, he presented deep vein thrombosis (DVT) of the lower limbs and was treated with unfractionated heparin. This case report illustrates the pathophysiology of DVT occurring in a patient with chicken pox disease (i.e., acquired protein C and S deficiencies and anti-protein S autoantibodies) and emphasizes the utility of thrombophilia testing in order to better adapt treatment.

Therapeutic recombinant murine activated protein C attenuates pulmonary coagulopathy and improves survival in murine pneumococcal pneumonia.

BACKGROUND: Recombinant human activated protein C (APC) improves survival of patients with severe sepsis; this beneficial effect is especially apparent in patients with pneumococcal pneumonia. The aim of this study was to determine the effect of APC treatment initiated after induction of pneumococcal pneumonia on pulmonary coagulation, inflammation, and survival, with or without concurrent antibiotic therapy. METHODS: Mice were infected intranasally with viable Streptococcus pneumoniae and were treated intraperitoneally after 24 h of infection with vehicle, recombinant mouse (rm) APC (125 µg), ceftriaxone (500 µg), or rm-APC plus ceftriaxone. Treatment with rm-APC or vehicle was repeated every 8 h for a maximum of 96 h. Animals were either killed 48 h after infection or were monitored in a survival study (with an extra dose of ceftriaxone given after 72 h). RESULTS: Rm-APC treatment inhibited pulmonary activation of coagulation, as reflected by lower levels of thrombin-antithrombin complexes and D-dimer. Rm-APC did not affect the pulmonary levels of 55 inflammatory mediators in the context of antibiotic therapy. Rm-APC added to ceftriaxone markedly improved survival, compared with ceftriaxone treatment alone. CONCLUSIONS: Rm-APC inhibits pulmonary activation of coagulation and, when added to antibiotic therapy, improves survival in murine pneumococcal pneumonia.

Activated protein C improves heatstroke outcomes through restoration of normal hypothalamic and thermoregulatory function.

BACKGROUND: Human recombinant activated protein C (APC) has been found to be beneficial in treating heatstroke in both humans and rats. Here, we further investigated the possible mechanism underlying the therapeutic action exerted by APC in experimental heatstroke. METHODS: Unanesthetized and unrestrained mice were exposed to an ambient temperature of 42.4 degrees C for 1 hour to induce heatstroke. They were given normal saline or APC (5 mg/kg of body weight, intravenously) 1 hour after the termination of heat stress. Their physiologic and biochemical parameters were continuously monitored for 4 hours after cessation of heat stress. Mice that survived on day 4 of heat treatment were considered survivors. RESULTS: When the vehicle-treated mice underwent heat treatment, the fraction survival and core temperature at 4 hours of body heating were found to be 0 of 12 and 33.8 +/- 0.6 degrees C, respectively. Administration of APC 1 hour after the cessation of heat stress rescued the mice from heat-induced death (fraction survival, 12 of 12) and reduced hypothermia (core temperature, 37.4 +/- 0.2 degrees C). Heat-induced apoptosis in the hypothalamus was significantly reduced by APC. The increased levels of cellular ischemia (eg, glutamate, lactate-to-pyruvate ratio, nitrite, and dihydroxybenzoic acid) and damage (eg, glycerol) markers in the hypothalamus during heatstroke were also decreased significantly by APC therapy. The hypothalamic levels of tumor necrosis factor-alpha (a proinflammatory cytokine) that are upregulated in heat-stressed mice were significantly lower in APC-administered mice. CONCLUSIONS: Our results show that human recombinant APC improves heatstroke through restoration of normal hypothalamic and thermoregulatory function.

Tirofiban and activated protein C synergistically inhibit the Instant Blood Mediated Inflammatory Reaction (IBMIR) from allogeneic islet cells exposure to human blood.

Instant blood mediated inflammatory reaction (IBMIR) occurs when islets are exposed to blood and manifests clinically as portal vein thrombosis and graft failure. The aim of this study was to determine the impact of recombinant human activated protein C (rhAPC) and platelet inhibition on IBMIR in order to develop a better targeted treatment for this condition. Five thousand human islet cell equivalents (IEQ) were mixed in a PVC loop system with 7 mL of ABO compatible human blood and incubated with rhAPC, either alone or in combination with tirofiban. Admixing human islets and blood caused rapid clot formation, consumption of platelets, leukocytes, fibrinogen, coagulation factors and raised d-dimers. Islets were encased in a fibrin and platelet clot heavily infiltrated with neutrophils. Tirofiban monotherapy was ineffective, whereas rhAPC monotherapy prevented IBMIR in a dose-dependent manner, preserving islet integrity while maintaining platelet and leukocyte counts, fibrinogen and coagulation factor levels, and reducing d-dimer formation. The combination of tirofiban and low-dose rhAPC inhibited IBMIR synergistically with an efficacy equal to high dose rhAPC. Tirofiban and rhAPC worked synergistically to preserve islets, suggesting that co-inhibition of the platelet and coagulation pathways' contribution to thrombin generation is required for the optimal anti-IBMIR effect.

Successful protein C concentrate administration during initiation of oral anticoagulation in adult patients with severe congenital protein C deficiency: report of two cases.

Protein C (PC) is a vitamin K-dependent proenzyme with anticoagulant activity, and patients with congenital PC deficiency are at high risk for thrombotic episodes. In patients with PC deficiency, starting treatment with oral anticoagulant drugs is associated with a transient hypercoagulable state and clinically overt thromboembolic complications before reaching a full anticoagulant effect. This report describes a successful supplementation with PC concentrate in two adult patients with moderately severe PC deficiency during the initiation of oral anticoagulation and a course of therapeutic dose of low-molecular-weight heparin for acute venous thromboembolism. Plasma PC levels above 50% were observed in both patients and maintained during the entire supplementation treatment period with PC concentrate until a stable therapeutic anticoagulation level has been reached. These results have been obtained within a short time, thus allowing a safe administration of a loading dose of warfarin. No adverse reactions to the PC concentrate, i.e. skin necrosis and other thromboembolic complications, bleedings or allergic reactions, were observed. We conclude that PC concentrate seems to be effective for the prevention of thromboembolic complications and safe in patients with congenital PC deficiency while initiating oral anticoagulants.

Antithrombotic and anticoagulant effects of wild type and Gla-domain mutated human activated protein C in rats.

The antithrombotic and anticoagulant effects of recombinant wild type (WT) and mutated human activated protein C (hAPC) were investigated using a rat model of arterial thrombosis. Recent in vitro studies using human plasma have shown enhanced anticoagulant effects of hAPC by mutagenesis of either loop 148 in the serine protease domain or of the Gla domain. The Gla-domain mutant QGNSEDY-hAPC (= H10Q/S11G/S12N/D23S/Q32E/N33D/H44Y) was found to be particularly active as an anticoagulant. We now combined the two mutations to create the variant QGNSEDY-hAPC:B148 and investigated the in vivo effects of this variant as well as of QGNSEDY-hAPC and WT hAPC using a rat model of arterial thrombosis. In vitro clotting experiments using rat plasma demonstrated WT hAPC to be inefficient, whereas both mutant hAPC variants yielded distinct dose dependent anticoagulant effects. In the arterial injury model, a segment of the left common carotid artery was opened longitudinally. An endarterectomy was performed and the arteriotomy was closed, whereafter the vessel was reperfused and the patency rate determined after 31 min. Three treatment groups each containing 10 rats and a control group of 20 animals were in a blind random fashion given intravenous bolus injections of 0.8 mg/kg WT or mutant hAPC or vehicle only. The ex vivo clotting times of plasma drawn 3 min after the injections, as compared to baseline clotting times, were approximately doubled by QGNSEDY-hAPC and tripled by QGNSEDY-hAPC:B148 infusions, while WT APC had little effect. Compared to the control group, none of the hAPC preparations had significant antithrombotic effect or increased arteriotomy bleeding.

Physical and chemical compatibility of drotrecogin alfa (activated) with 34 drugs during simulated Y-site administration.

PURPOSE: The physical and chemical compatibility of drotrecogin alfa (activated) (recombinant human activated protein C) during simulated Y-site administration with drugs commonly used to treat patients with severe sepsis was determined. METHODS: Thirty-four drugs were investigated for visual compatibility with drotrecogin alfa, and included cardiovascular agents, conscious sedative agents, antibiotics, blood products, and other supportive care drugs. The physical and chemical compatibility of drotrecogin alfa with these drugs was determined using a well-established experimental model to simulate Y-site administration. Drotrecogin alfa (activated) was prepared as 100- and 1000-microg/mL solutions in 0.9% sodium chloride injection. All other drugs were prepared at maximum concentrations commonly administered in the clinical setting. Visual compatibility was assessed by visual inspection (observations of haziness, color change, or precipitate formation) and pH measurement at 0, 30, 60, and 240 minutes after mixing. RESULTS: Of the 34 test drugs, 8 were defined as visually compatible with drotrecogin alfa; these drugs were further assessed for chemical compatibility with drotrecogin alfa. The protein content, potency, and purity of drotrecogin alfa were determined at 0, 60, and 240 minutes after Y-site mixing as indicators of chemical compatibility. Six drugs (ceftriaxone, cisatracurium, fluconazole, nitroglycerin, potassium chloride, and vasopressin) were determined to be chemically compatible with drotrecogin alfa; two drugs (cyclosporine and ticarcillin-clavulanate) were chemically incompatible with drotrecogin alfa after Y-site mixing. CONCLUSION: Ceftriaxone, cisatracurium, fluconazole, nitroglycerin, potassium chloride, and vasopressin were physically and chemically compatible with drotrecogin alfa in a simulated Y-site infusion; 28 other drugs were incompatible with drotrecogin alfa.

Activated human protein C prevents thrombin-induced thromboembolism in mice. Evidence that activated protein c reduces intravascular fibrin accumulation through the inhibition of additional thrombin generation.

Activated protein C (APC) is a potent physiologic anticoagulant with profibrinolytic properties, and has been shown to prevent thrombosis in different experimental models. We investigated the effect of human APC on thrombin-induced thromboembolism in mice, a model of acute intravascular fibrin deposition leading to death within minutes. APC given intravenously (i.v.) as a bolus 2 min before thrombin challenge (1,250 U/kg) reduced mortality in a dose-dependent manner despite the lack of thrombin inhibitor activity. Significant inhibition of thrombin-induced death was observed at the dose of 0.05 mg/kg, and maximal protection was obtained with 2 mg/kg (> 85% reduction in mortality rate). Histology of lung tissue revealed that APC treatment (2 mg/kg) reduced significantly vascular occlusion rate (from 89.2 to 46.6%, P < 0.01). The protective effect of APC was due to the inhibition of endogenous thrombin formation as indicated by the fact that (a) the injection of human thrombin caused a marked decrease in the coagulation factors of the intrinsic and common pathways (but not of Factor VII), suggesting the activation of blood clotting via the contact system; (b) APC pretreatment reduced markedly prothrombin consumption; (c) the lethal effect of thrombin was almost abolished when the animals were made deficient in vitamin K-dependent factors by warfarin treatment, and could be restored only by doubling the dose of thrombin, indicating that the generation of endogenous thrombin contributes significantly to death; and (d) APC failed to protect warfarin-treated animals, in which mortality is entirely due to injected thrombin, even after protein S supplementation. Other results suggest that APC protects from thrombin-induced thromboembolism by rendering the formed fibrin more susceptible to plasmin degradation rather than by reducing fibrin formation: in thrombin-treated mice, fibrinogen consumption was not inhibited by APC; and inhibition of endogenous fibrinolysis by epsilon-aminocaproic or tranexamic acid resulted in a significant reduction of the protective effect of APC. Since APC did not enhance plasma fibrinolytic activity, as assessed by the measurement of plasminogen activator (PA) or PA inhibitor (PAI) activities, PAI-1 antigen, or 125I-fibrin degrading activity, we speculate that the inhibition of additional (endogenous) thrombin formation by APC interrupts thrombin-dependent mechanisms that make fibrin clots more resistant to lysis, so that the intravascular deposited fibrin can be removed more rapidly by the endogenous fibrinolytic system.