Serpins (serine protease inhibitors) are a large family of structurally related proteins found in a wide variety of organisms, including hematophagous arthropods. Protein analyses revealed that Iris, previously described as an immunomodulator secreted in the tick saliva, is related to the leukocyte elastase inhibitor and possesses serpin motifs, including the reactive center loop (RCL), which is involved in the interaction between serpins and serine proteases. Only serine proteases were inhibited by purified recombinant Iris (rIris), whereas mutants L339A and A332P were found devoid of any protease inhibitory activity. The highest K a was observed with human leukocyteelastase, suggesting that elastase-like proteases are the natural targets of Iris. In addition, mutation M340R completely changed both Iris substrate specificity and affinity. This likely identified Met-340 as amino acid P1 in the RCL. The effects of rIris and its mutants were also tested on primary hemostasis, blood clotting, and fibrinolysis. rIris increased platelet adhesion, the contact phase-activated pathway of coagulation, and fibrinolysis times in a dose-dependent manner, whereas rIris mutant L339A affected only platelet adhesion. Taken together, these results indicate that Iris disrupts coagulation and fibrinolysis via the anti-proteolytic RCL domain. One or more other domains could be responsible for primary hemostasis inhibition. To our knowledge, this is the first ectoparasite serpin that interferes with both hemostasis and the immune response.Ticks are blood-sucking arthropods that infest a large variety of vertebrate hosts (mammals, birds, reptiles, and amphibians) in many parts of the world (1). To complete their blood meal, blood-sucking arthropods express a wide range of anti-hemostatic molecules in their saliva, including vasodilators, inhibitors of the platelet aggregation, and anti-coagulants (2). Tick saliva and salivary gland extracts are also known to modulate the host's defense mechanisms (3-6). Both anti-hemostatic and immunosuppressive compounds were identified, isolated, and characterized from soft and hard ticks. These compounds include histamine-binding proteins, tissue factor pathway inhibitor-like proteins, anti-thrombin-like proteins, and anticomplement factors (7-16).These last years, several laboratories reported the construction and screening of cDNA libraries from tick salivary glands. Thus, Das et al. (17) found 14 Ixodes scapularis immunodominant antigens, whereas Leboulle et al. (18) identified 27 mRNA, the expression of which is specifically induced or up-regulated during the Ixodes ricinus blood meal. Finally, Ribeiro and coworkers explored the sialome of the tick I. scapularis (19,20) and uncovered a large variety of putative bioactive agents. These studies all identified some serine protease inhibitors, containing serpin, kunitz, kazal, or ␣-macroglobulin motifs (21).To date, ϳ500 serpins have been identified in a large variety of species, including animals, viruses, and plants. On average, serpins are 35...

Blood coagulation starts immediately after damage to the vascular endothelium. This system is essential for minimizing blood loss from an injured blood vessel but also contributes to vascular thrombosis. Although it has long been thought that the intrinsic coagulation pathway is not important for clotting in vivo, recent data obtained with genetically altered mice indicate that contact phase proteins seem to be essential for thrombus formation. We show that recombinant Ixodes ricinus contact phase inhibitor (Ir-CPI), a Kunitz-type protein expressed by the salivary glands of the tick Ixodes ricinus, specifically interacts with activated human contact phase factors (FXIIa, FXIa, and kallikrein) and prolongs the activated partial thromboplastin time (aPTT) in vitro. The effects of Ir-CPI were also examined in vivo using both venous and arterial thrombosis models. Intravenous administration of Ir-CPI in rats and mice caused a dose-dependent reduction in venous thrombus formation and revealed a defect in the formation of arterial occlusive thrombi. Moreover, mice injected with Ir-CPI are protected against collagen- and epinephrine-induced thromboembolism. Remarkably, the effective antithrombotic dose of Ir-CPI did not promote bleeding or impair blood coagulation parameters. To conclude, our results show that a contact phase inhibitor is an effective and safe antithrombotic agent in vivo.

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Background: Recent reports have identified the apnoea and hypopnoea index (AHI) as an additional independent risk factor for cardiovascular morbidity and mortality. However, several studies reported contradictory results about the association between the serum C-reactive protein (CRP) level and the severity of apnoea. Objective: The purpose of this work is to study this association in patients referred to the sleep laboratory for clinical suspicion of sleep apnoea and presenting a wide range of AHI. Methods: Forty-nine consecutive patients were included in the study. The SigmaStat^® software package (Jandle Scientific) was used. Multilinear regression analysis was tested using a stepwise backward selection of the explicative variables. The clinical characteristics (diabetes, hypertension, smoking habits, gender) were treated as dichotomous variables, while all other data (age, BMI, lipids, white blood cells) were continuous ones; high-sensitivity (hs)-CRP was the dependent variable. Results: In univariate analysis, AHI was correlated to hs-CRP: R = 0.43, p = 0.002. In multivariate analyses, we found an independent association between the AHI, adjusted for classical cardiovascular risk factors, and hs-CRP. Conclusion: In a sample of 49 patients, referred to the sleep laboratory for suspicion of sleep apnoea in routine practice, we observed an independent association between the AHI and hs-CRP.

Background: Determination of clot lysis times on whole blood, diluted whole blood, plasma or plasma fraction has been used for many years to assess the overall activity of the fibrinolytic system. We designed a completely computerised semi-automatic 8-channel device for measurement and determination of fibrin clot lysis. The lysis time is evaluated by a mathematical analysis of the lysis curve and the results are expressed in minute (range: 5 to 9999). We have used this new device for Euglobulin Clot Lysis Time (ECLT) determination, which is the most common test used in laboratories to estimate plasma fibrinolytic capacity.

In conclusion, the utility of the long exposure of patients with benign respiratory infections to azithromycin and to subinhibitory concentrations of azithromycin should be questioned.

The meaning, the utility, and the prognostic significance of the International Society of Thrombosis and Hemostasis overt disseminated intravascular coagulation (DIC) score and other parameters of coagulation activation including soluble fibrin monomer complexes (SFMC), antithrombin and protein C consumption, and formation of lipoprotein-C-reactive protein (LP-CRP) complexes (MDA slope 1 and flag A2) were evaluated in 165 inpatients from a general hospital for whom DIC testing was required by the attending physicians. Of these 165 patients, 148 had an underlying disease that clearly justified the laboratory request from our systematic post hoc review of the clinical charts. Of these 148 patients, 28 had a positive overt DIC score, 19 had an A2 flag, and 4 had both. The DIC score was strongly related to several major markers of coagulation activation such as D-dimers, thrombin-antithrombin complexes, and soluble fibrin and was inversely related to antithrombin and protein C levels, which began to fall from DIC score 4 or higher. The formation of LP-CRP complexes was only related to Gram-negative sepsis and these patients had a strong inflammatory reaction. Independent risk factors for death were high creatininemia, positive overt DIC score, and/or presence of SFMC. In patients with positive DIC score, SFMC positivity and low levels of antithrombin and/or protein C were additional risk factors. The ISTH overt DIC score proves useful and adequate as a marker for clinically significant DIC. Illness severity is further defined by SFMC, antithrombin, and protein C levels. LP-CRP complexes are related to sepsis but not to actual overt DIC and lethal prognosis.

minimal bactericidal concentration of amoxycillin was 27-4 tmol/l (10-0 pg/ml) but the minimal inhibitory concentration was only 0 07 ,umol/l (0-025 [&g/ml); the failed prophylaxis against this relatively tolerant pathogen was ascribed to persistent exposure to largeinocula. Fromour dataeven ninehours after takingamoxycillin serum concentrations exceeding the minimal inhibitory-concentration (0-07 pmol/l) were likely but bactericidal concentrations pmol/l) would not have occurred. Clearly, even if amoxycillin concentrations exceed the minimal inhibitory concentration for prolonged periods failure to maintain bactericidal values may be critical.Our study suggests that nine hours after a 3 g dose of oral amoxycillin syrup (eight hours after dentistry) serum is not necessarily bactericidal against relatively resistant pathogenic strains of viridans streptococci in about half of all patients. Hence whenever the possibility of infection with viridans streptococci warrants a second dose of amoxycillin this should not be left till eight hours after the procedure as recommended hitherto.I By repeating the dose after about four hours, however, more effective prophylaxis may be obtained even against relatively resistant species.We thank the University of Hong Kong dental and medical faculties and Beecham Pharmaceuticals for financial support and facilitating this work. We are also indebted to Professor C E Renson for his helpful advice and encouragement. The hyponatraemia common in decompensated cirrhosis arises in part from secretion of antidiuretic hormone attributed to a decrease in effective blood volume. Baroreceptors send inhibitory impulses to the midbrain and hypothalamus through the vagus and glossopharyngeal nerves. Since vagal neuropathy often occurs in chronic alcoholism, this might theoretically contribute to the inappropriate secretion of antidiuretic hormone, which might in turn induce hyponatraemia. In a prospective study including 34 patients with cirrhosis a high incidence ofvagal neuropathy was found in the alcoholics (64%) and a clear cut increase in the incidence of hyponatraemia in patients with evidence of vagal damage and ascites (seven of eight patients (88%); p=002). Results of a retrospective study of 64 patients with cirrhosis and ascitic decompeusation showed hyponatraemia in 17 (50%) of 34 alcoholics but in only four (13%) of 30 patients with non-alcoholic disease (p=0.006).Vagal neuropathy in alcoholic cirrhosis may contribute to the low serum sodium concentrations commonly found in these patients. IntroductionThe hyponatraemia commonly found in cirrhosis-is generally attributed to an excessive secretion of antidiuretic hormone despite hypo-osmolality of the blood.' The classical theory suggests that patients with decompensated disease have a decrease in the "effective" central blood volume resulting in decreased vagal and glossopharyngeal afferent influx to the midbrain and hypothalamus. The decreased afferent neural input is associated with a non-osmotic release of antidiuretic hormone a...