Experimental study on the hemostatic effect of cyanoacrylate intended for catheter securement.

PURPOSE:: The use of cyanoacrylate for intravenous catheter securement is of interest to clinicians and patients, because of the superior adhesive strength and hemostatic effect of cyanoacrylate compared to current securement devices. The purpose of this study is to use novel in vitro and in vivo testing methods to analyze the hemostatic effect of a catheter securement cyanoacrylate (cyanoacrylate). METHODS:: An unprecedented in vitro method was performed to determine the effects of a cyanoacrylate on a customized modified activated clotting time assay and blood flow inhibition assay by exposing blood or plasma to either one or three drops of cyanoacrylate. For the in vivo testing, full-thickness incisions were made on swine, and the bleeding was scored prior to treatment and at 3, 6, 9, and 12 min after treatment. RESULTS:: The cyanoacrylate rapidly achieved hemostasis in the presence of anticoagulated whole blood, platelet-poor plasma, and non-anticoagulated whole blood, in vitro. The cyanoacrylate achieved hemostasis 12-fold faster than thromboplastin in the modified activated clotting time assay. The cyanoacrylate does not alter normal blood clotting, as measured by prothrombin time. In vivo, the bleeding score of cyanoacrylate prior to treatment and at 3, 6, 9, and 12 min after treatment were 2.3 ± 1.0, 0.3 ± 0.5, 0.2 ± 0.5, 0.2 ± 0.4, and 0.2 ± 0.4, respectively. CONCLUSION:: This study indicates that cyanoacrylate demonstrates a potent mechanical hemostatic effect and cyanoacrylate in the presence of anticoagulated whole blood has an activated clotting time that is 12 times quicker than thromboplastin. The cyanoacrylate was found to be significantly equivalent to two known hemostatic agents, in vivo.

Toxicological and toxicokinetic analysis of angiotensin (1-7) in two species.

The objectives of this study were to determine the potential systemic and local toxicity, as well as evaluate the toxicokinetic (TK) profile of angiotensin (1-7) [A(1-7)] when administered daily via subcutaneous injection for 28 days to Sprague-Dawley rats and Beagle dogs. A(1-7) is a member of the renin-angiotensin system and has undergone clinical evaluation for the treatment of chemotherapy-induced myelosuppression. In this present study, A(1-7) was given at 10 mg/(kg day) for 28 days to rats and canines. At day 27, blood was harvested to evaluate the TK parameters. On day 28, systemic toxicology was evaluated. Following A(1-7) administration for 27 days, no plasma A(1-7) accumulation was detected in canines; however, increased A(1-7) plasma concentrations were detected in rats. Despite the accumulation observed in rats, no detectable toxicity was found following A(1-7) administration for 28 days. The TK analysis of A(1-7) revealed a plasma half-life of 20-30 min in both rats and canines. The time to maximum plasma concentration was found to be 15 and 26.25 min in rats and canines, respectively. This study shows that subcutaneous administration of A(1-7) at 10 mg/(kg day) for 28 days did not lead to any detectable toxicities in either rats or canines.

Reactive nitrogen species in acetaminophen-induced mitochondrial damage and toxicity in mouse hepatocytes.

Acetaminophen (APAP) toxicity in primary mouse hepatocytes occurs in two phases. The initial phase (0-2 h) occurs with metabolism to N-acetyl-p-benzoquinoneimine which depletes glutathione, and covalently binds to proteins, but little toxicity is observed. Subsequent washing of hepatocytes to remove APAP and reincubating in media alone (2-5 h) results in toxicity. We previously reported that the reincubation phase occurs with mitochondrial permeability transition (MPT) and increased oxidative stress (dichlorodihydrofluorescein fluorescence) (DCFH(2)). Since DCFH(2) may be oxidized by multiple oxidative mechanisms, we investigated the role of reactive nitrogen species (RNS) leading to 3-nitrotyrosine in proteins by ELISA and by immunoblots. Incubation of APAP with hepatocytes for 2 h did not result in toxicity or protein nitration; however, washing hepatocytes and reincubating in media alone (2-5 h) resulted in protein nitration which correlated with toxicity. Inclusion of the MPT inhibitor, cyclosporine A, in the reincubation media eliminated toxicity and protein nitration. The general nitric oxide synthase (NOS) inhibitor L-NMMA and the neuronal NOS (NOS1) inhibitor, 7-nitroindazole, added in the reincubation media decreased toxicity and protein nitration; however, neither the inducible NOS (NOS2) inhibitors L-NIL (N6-(1-iminoethyl)-L-lysine) nor SAIT (S-(2-aminoethyl)isothiourea) decreased protein nitration or toxicity. The RNS scavengers, N-acetylcysteine, and high concentrations of APAP, added in the reincubation phase decreased toxicity and protein nitration. 7-Nitroindazole and cyclosporine A inhibited the APAP-induced loss of mitochondrial membrane potential when added in the reincubation phase. The data indicate a role for RNS in APAP induced toxicity.

Mechanisms of chloroform-induced hepatotoxicity: oxidative stress and mitochondrial permeability transition in freshly isolated mouse hepatocytes.

The role of mitochondrial permeability transition (MPT) and oxidative stress in chloroform toxicity was determined in freshly isolated female B6C3F1 mouse hepatocytes. Incubation of chloroform (12 mM) with hepatocytes resulted in cell death (alanine aminotransferase release and propidium iodide fluorescence). Chloroform had volatilized from the incubation and glutathione was depleted by 1 h; however, toxicity was not significantly different between control and chloroform-incubated cells. Hepatocytes were washed and reincubated in fresh media at 1 h. Subsequent reincubation of chloroform-treated hepatocytes resulted in significant toxicity at 3-5 h. Inclusion of the MPT inhibitor cyclosporine A or the antioxidant N-acetylcysteine (NAC) in the reincubation media at 1 h prevented toxicity. Confocal microscopy studies with the dye calcein AM indicated MPT that was blocked by cyclosporine A or NAC. Fluorescence microscopy studies utilizing JC-1 indicated loss of mitochondrial membrane potential, which was also blocked by cyclosporine A or NAC. Dichlorofluorescein fluorescence increased during the reincubation phase, indicating increased oxidative stress, and the increase was blocked by cyclosporine A. Since oxidative stress may occur by peroxynitrite, its role in toxicity was examined. Either of the nitric oxide synthase inhibitors N(G)-methyl-L-arginine (L-NMMA) and 7-nitroindazole (7-NI) at 1 h blocked toxicity. Western blot analysis of hepatocytes for 3-nitrotyrosine in proteins, a biomarker of peroxynitrite, indicated one major nitrated protein at 81 kD. Nitration of this protein was inhibited by cyclosporine A, L-NMMA, 7-NI, or NAC. The data indicate that chloroform-induced cell death occurs in two phases: a metabolic phase characterized by glutathione depletion, and an oxidative phase characterized by MPT and protein nitration.

Induction of the nuclear factor HIF-1alpha in acetaminophen toxicity: evidence for oxidative stress.

Hypoxia inducible factor (HIF) controls the transcription of genes involved in angiogenesis, erythropoiesis, glycolysis, and cell survival. HIF-1alpha levels are a critical determinant of HIF activity. The induction of HIF-1alpha was examined in the livers of mice treated with a toxic dose of APAP (300 mg/kg i.p.) and sacrificed at 1, 2, 4, 8, and 12 h. HIF-1alpha was induced at 1-12 h and induction occurred prior to the onset of toxicity. Pre-treatment of mice with N-acetylcysteine (1200 mg/kg i.p.) prevented toxicity and HIF-1alpha induction. In further studies, hepatocyte suspensions were incubated with APAP (1 mM) in the presence of an oxygen atmosphere. HIF-1alpha was induced at 1 h, prior to the onset of toxicity. Inclusion of cyclosporine A (10 microM), an inhibitor of mitochondrial permeability transition, oxidative stress, and toxicity, prevented the induction of HIF-1alpha. Thus, HIF-1alpha is induced before APAP toxicity and can occur under non-hypoxic conditions. The data suggest a role for oxidative stress in the induction of HIF-1alpha in APAP toxicity.