Time-dependent systemic hemostatic effects of fibrin monomer in controlled liver injury in the experiment

Aim. To evaluate the hemostatic effect of fibrin monomer after its intravenous administration at different time periods in experimental trauma. Methods. In the experiments, in a placebo-controlled study, hemostatic and hemostasiological effects of systemic use of fibrin monomer were studied at different time periods after its administration (in 5 min, 1 h and 3 h) in 97 male rabbits of the Chinchilla breed in the controlled liver injury model. Results. A pronounced hemostatic effect was demonstrated for fibrin monomer used at a dose of 0.25 mg/kg demonstrated by a 6.3-fold decrease of blood loss volume (% of circulating blood volume) compared to placebo on the background of the intravenous preventive fibrin monomer administration 1 hour prior to controlled liver injury. Fibrin monomer administration at a stated dose was not accompanied by significant changes in haemocoagulative parameters including measurement of platelet count, activated partial thromboplastin time, prothrombin time, thrombin time, echitox time, fibrinogen concentration, level of soluble fibrin monomer complexes, D-dimer content, and antithrombin III activity. The effect of fibrin monomer is probably realized through some effectors, the nature of which has not yet been studied. The obtained results allow choosing the optimal interval between intravenous administrations of fibrin monomer and controlled liver injury for further study of the mechanisms of its hemostatic action. Conclusion. Fibrin monomer in small doses (0.25 mg/kg) is able to exert a pronounced hemostatic effect with its systemic administration 1 hour prior to the injury without significant changes in haemocoagulative parameters

Enzymatic Mechanisms Involved in Evasion of Fungi to the Oxidative Stress: Focus on Scedosporium apiospermum

The airways of patients with cystic fibrosis (CF) are frequently colonized by various filamentous fungi, mainly Aspergillus fumigatus and Scedosporium species. To establish within the respiratory tract and cause an infection, these opportunistic fungi express pathogenic factors allowing adherence to the host tissues, uptake of extracellular iron, or evasion to the host immune response. During the colonization process, inhaled conidia and the subsequent hyphae are exposed to reactive oxygen species (ROS) and reactive nitrogen species (RNS) released by phagocytic cells, which cause in the fungal cells an oxidative stress and a nitrosative stress, respectively. To cope with these constraints, fungal pathogens have developed various mechanisms that protect the fungus against ROS and RNS, including enzymatic antioxidant systems. In this review, we summarize the different works performed on ROS- and RNS-detoxifying enzymes in fungi commonly encountered in the airways of CF patients and highlight their role in pathogenesis of the airway colonization or respiratory infections. The potential of these enzymes as serodiagnostic tools is also emphasized. In addition, taking advantage of the recent availability of the whole genome sequence of S. apiospermum, we identified the various genes encoding ROS- and RNS-detoxifying enzymes, which pave the way for future investigations on the role of these enzymes in pathogenesis of these emerging species since they may constitute new therapeutics targets

The transition between active and de-activated forms of NADH:ubiquinone oxidoreductase (Complex I) in the mitochondrial membrane of Neurospora crassa.

The mammalian mitochondrial NADH:ubiquinone oxidoreductase (Complex I) has been shown to exist in two kinetically and structurally distinct slowly interconvertible forms, active (A) and de-activated (D) [Vinogradov and Grivennikova (2001) IUBMB Life 52, 129-134]. This work was undertaken to investigate the putative Complex I A-D transition in the mitochondrial membrane of the lower eukaryote Neurospora crassa and in plasma membrane of the prokaryote Paracoccus denitrificans, organisms that are eligible for molecular genetic manipulations. The potential interconversion between A and D forms was assessed by examination of the initial and steady-state rates of NADH oxidation catalysed by inside-out submitochondrial ( N. crassa ) and sub-bacterial ( P. denitrificans ) particles and their sensitivities to N -ethylmaleimide and Mg(2+). All diagnostic tests provide evidence that slow temperature- and turnover-dependent A-D transition is an explicit feature of eukaryotic N. crassa Complex I, whereas the phenomenon is not seen in the membranes of the prokaryote P. denitrificans. Significantly lower activation energy for A-to-D transition characterizes the N. crassa enzyme compared with that determined previously for the mammalian Complex I. Either a lag or a burst in the onset of the NADH oxidase assayed in the presence of Mg(2+) is seen when the reaction is initiated by the thermally de-activated or NADH-activated particles, whereas the delayed final activities of both preparations are the same. We conclude that continuous slow cycling between A and D forms occurs during the steady-state operation of Complex I in N. crassa mitochondria

SYSTEMIC HEMOSTATIC AND PROTHROMBOTIC EFFECTS OF FIBRIN-MONOMER IN EXPERIMENT WITH DOSED LIVER THERAPY

Objective of the study is to experimentally evaluate system hemostatic and prothrombotic effects of intravenous fibrin monomer (FM). Materials and methods. Eighty two Chinchilla rabbits weighing 3–4 kg were used in the study. In addition to the placebo, animals were administered an aqueous solution of fibrin monomer (FM) intravenously at doses of 0.1, 0.25, 0.5, 1.0, 2.5 and 5.0 mg/kg. After 1 hour, a standard liver injury was performed and the blood loss (% of the circulating blood volume) resulting from parenchymal hemorrhage was estimated. Hemostatic system examination included platelet number in venous blood and fibrinogen and D-dimer levels in blood plasma. Results and discussion. Blood loss after dosed injury with placebo was 10.0 [4.0; 15.7] % blood volume (median [25th percentile; 75th percentile]). FM preparation doses of 0.25, 2.5 and 5.0 mg/kg resulted in a decrease of blood loss by 6.3 (p < 0.001), 7.8 (p < 0.001) and 2.7 times (p = 0.04) (1.6 [1.0; 3.0], 1.3 [0.6; 1,6] and 3.7 [2.8; 5.3] % blood volume, respectively).High doses of FM preparation (2.5 and 5.0 mg/kg) minimized blood loss due to activation of coagulation and thrombus formation, which was illustrated by a 7.0–8.0-fold increase in D-dimer level (compared to placebo). 0.25 mg/kg of FM preparation did not lead to an increase of D-dimer content, although the blood loss was greatly reduced. Conclusion. The data obtained show the presence of unique hemostatic properties in low-dose FM preparation (0.25 mg/kg), which allows creating system hemostatic agents of a new generation