Defence Anaesthesia transition from the Tri-Service Anaesthetic Apparatus to the Diamedica Portable Anaesthesia Machine 02

Defence Anaesthesia is changing its draw-over anaesthetic capability from the Tri-Service Anaesthetic Apparatus (TSAA) to the Diamedica Portable Anaesthesia Machine 02 (DPA02). The DPA02 will provide a portable, robust, lightweight and simple method for delivering draw-over volatile anaesthesia with the option of positive pressure ventilation through manual or mechanical operation for paediatric and adult patients. The UK Defence Medical Services uses a modified configuration of the DPA02; this paper seeks to explain the rationale for the differing configurations and illustrates alternative assemblies to support integration with other Defence Anaesthesia equipment. High-fidelity simulation training using the DPA02 will continue to be delivered on the Defence Anaesthesia Simulation Course (DASC). Conformité Européenne accreditation of DPA02 supports future UK live patient training in centres of excellence supervised by subject matter experts; this was not possible with the TSAA. This article is intended to be a key reference for all members of the Defence Anaesthesia team. Alongside other resources, it will be given as precourse learning prior to attending the DASC and the Military Operational Surgical Training. This article will also be issued with all Defence DPA02 units, supporting ease of access for review during future clinical exercises (including validation), prior to supervised live training and on operational deployments.

Systematic review of the anaesthetic management of non-iatrogenic acute adult airway trauma

INTRODUCTION

Non-iatrogenic trauma to the airway is rare and presents a significant challenge to the anaesthetist. Although guidelines for the management of the unanticipated difficult airway have been published, these do not make provision for the 'anticipated' difficult airway. This systematic review aims to inform best practice and suggest management options for different injury patterns.

METHODS

A literature search was conducted using Embase, Medline, and Google Scholar for papers after the year 2000 reporting on the acute airway management of adult patients who suffered airway trauma. Our protocol and search strategy are registered with and published by PROSPERO (http://www.crd.york.ac.uk/PROSPERO, ID: CRD42016032763).

RESULTS

A systematic literature search yielded 578 articles, of which a total of 148 full-text papers were reviewed. We present our results categorized by mechanism of injury: blunt, penetrating, blast, and burns.

CONCLUSIONS

The hallmark of airway management with trauma to the airway is the maintenance of spontaneous ventilation, intubation under direct vision to avoid the creation of a false passage, and the avoidance of both intermittent positive pressure ventilation and cricoid pressure (the latter for laryngotracheal trauma only) during a rapid sequence induction. Management depends on available resources and time to perform airway assessment, investigations, and intervention (patients will be classified into one of three categories: no time, some time, or adequate time). Human factors, particularly the development of a shared mental model amongst the trauma team, are vital to mitigate risk and improve patient safety.

An investigation into heterogeneity in a single vein-type uranium ore deposit: Implications for nuclear forensics

Minor element composition and rare earth element (REE) concentrations in nuclear materials are important as they are used within the field of nuclear forensics as an indicator of sample origin. However recent studies into uranium ores and uranium ore concentrates (UOCs) have shown significant elemental and isotopic heterogeneity from a single mine site such that some sites have shown higher variation within the mine site than that seen between multiple sites. The elemental composition of both uranium and gangue minerals within ore samples taken along a single mineral vein in South West England have been measured and reported here. The analysis of the samples was undertaken to determine the extent of the localised variation in key elements. Energy Dispersive X-ray spectroscopy (EDS) was used to analyse the gangue mineralogy and measure major element composition. Minor element composition and rare earth element (REE) concentrations were measured by Electron Probe Microanalysis (EPMA). The results confirm that a number of key elements, REE concentrations and patterns used for origin location do show significant variation within mine. Furthermore significant variation is also visible on a meter scale. In addition three separate uranium phases were identified within the vein which indicates multiple uranium mineralisation events. In light of these localised elemental variations it is recommended that representative sampling for an area is undertaken prior to establishing the REE pattern that may be used to identify the originating mine for an unknown ore sample and prior to investigating impact of ore processing on any arising REE patterns.

Endothelin-1 directs airway remodeling and hyper-reactivity in a murine asthma model

Background

The current paradigm describing asthma pathogenesis recognizes the central role of abnormal epithelial function in the generation and maintenance of the disease. However, the mechanisms responsible for the initiation of airway remodeling, which contributes to decreased lung function, remain elusive. Therefore, we aimed to determine the role of altered pulmonary gene expression in disease inception and identify proremodeling mediators.

Methods

Using an adenoviral vector, we generated mice overexpressing smad2, a TGF-β and activin A signaling molecule, in the lung. Animals were exposed to intranasal ovalbumin (OVA) without systemic sensitization.

Results

Control mice exposed to inhaled OVA showed no evidence of pulmonary inflammation, indices of remodeling, or airway hyper-reactivity. In contrast, local smad2 overexpression provoked airway hyper-reactivity in OVA-treated mice, concomitant with increased airway smooth muscle mass and peribronchial collagen deposition. Pulmonary eosinophilic inflammation was not evident, and there was no change in serum IgE or IgG1 levels. The profound remodeling changes were not mediated by classical pro-inflammatory Th2 cytokines. However, uric acid and interleukin-1β levels in the lung were increased. Epithelial-derived endothelin-1 and fibroblast growth factor were also augmented in smad2-expressing mice. Blocking endothelin-1 prevented these phenotypic changes.

Conclusions

Innate epithelial-derived mediators are sufficient to drive airway hyper-reactivity and remodeling in response to environmental insults in the absence of overt Th2-type inflammation in a model of noneosinophilic, noninflammed types of asthma. Targeting potential asthma therapies to epithelial cell function and modulation of locally released mediators may represent an effective avenue for therapeutic design.

Evidence for a regulatory role of alpha 4-integrins in the maturation of eosinophils generated from the bone marrow in the presence of dexamethasone

BACKGROUND

Although eosinophils co-express multiple integrin receptors, the contributions of integrins to eosinophil development have not been explored. We previously described extensive aggregation and cytological immaturity in eosinophils developing in bone-marrow (BM) cultures exposed to dexamethasone. Here we examined the relationship of alpha 4 integrins with these effects of dexamethasone.

OBJECTIVES

We evaluated: (a) the effects of exposure to dexamethasone in BM culture on eosinophil expression of alpha 4 integrin receptors and ligands; (b) the contribution of alpha 4 integrins to eosinophil aggregation and maturation.

METHODS

Cultures were established with IL-5 (alone or with dexamethasone) for up to 7 days, and eosinophil production, alpha 4 integrin receptor/ligand expression, aggregation and morphology were evaluated before and after targeting alpha 4 integrin-dependent adhesions. Because prostaglandin E2 (PGE2) modifies the effects of dexamethasone on eosinophilopoiesis, PGE2 effects on alpha 4 integrin expression and function were also evaluated.

RESULTS

Dexamethasone increased the yield of eosinophils up to day 7. The frequency of eosinophils expressing alpha 4, beta1 and beta 7 integrin receptors at day 7 was also increased by dexamethasone. Eosinophils also expressed the alpha 4 beta 1 ligand, VCAM-1. Dexamethasone increased the expression of alpha 4 integrin and VCAM-1 in aggregates containing eosinophils as early as day 3. PGE2, added up to day 3, modified the effects of dexamethasone to suppress the expression of alpha 4 integrin, decrease aggregation and promote cytological maturation of eosinophils recovered at day 7. Dissociation of immature eosinophils from clusters present at day 3 by reagents targeting alpha 4 or beta1 integrins or VCAM-1 also induced cytological maturation. The concordant effects of targeting alpha 4 integrins with drugs and antibodies support a relationship between alpha 4-mediated aggregation and maturational arrest.

CONCLUSIONS

These observations support a novel role for alpha 4 integrin receptors and ligands in eosinophilopoiesis. In addition, increased alpha 4 expression following glucocorticoid exposure may contribute to the retention and accumulation of eosinophils in haemopoietic tissue.

Development of normal human colon cell cultures to identify priority unregulated disinfection by-products with a carcinogenic potential

Research was initiated to develop an in vitro system to identify disinfection by-products with a potential to transform normal human colonocytes into malignant cells. Tribromomethane and bromochloroacetic acid, rodent colon carcinogens, dibromonitromethane and tribromonitromethane, recently identified in drinking water, and azoxymethane, a classic colon carcinogen, were tested for the ability to transform NCM460 cells. The chronic toxicity was determined for the series of trihalomethanes, haloacetic acids and halonitromethanes as well as NCM460 cell enzymatic capabilities. The order of cytotoxicity was halonitromethanes > haloacetic acids > trihalomethanes. Cytotoxicity within a series increased with the degree of bromination and decreased with the molecular weight. The genotoxicity profile was similar to that for cytotoxicity. Enzymatic analysis demonstrated that NCM460 cells possess glutathione-S transerase-1-1 and CYP450 activity similar to that measured in the large intestine. NCM460 cells were exposed to 10(-6) M of the test chemicals for three days. While NCM460 cells from all treatments had the ability to grow in soft agar to some extent, only cells exposed to azoxymethane or tribromomethane were able to grow in media lacking serum and growth factors. When sub cultured, NCM460 cells exposed to 10(-9) M azoxymethane for three weeks formed colonies with morphology distinct from untreated cells.

Rationale for the use of high dose rFVIIa in a high-titre inhibitor patient with haemophilia B during major orthopaedic procedures

Inhibitor development is a serious complication in patients with haemophilia A and B. Historically, a lack of optimal therapies and factor products for treating inhibitor patients resulted in many patients developing chronic haemophilic arthropathies and flexion contractures of the involved joints. The introduction of immune-tolerance protocols to eradicate high-titre inhibitors has greatly diminished the incidence of these types of complications but as in the case reported here, immune tolerance is not always successful. Various elective surgical procedures were often delayed or not even considered in patients with inhibitor because of the variability in achieving adequate haemostasis and the thrombotic risks involved with the use of activated prothrombin-complex concentrates (APCCs) over extended periods of time. The development of recombinant factor VIIa (rFVIIa; NovoSeven) and its demonstrated safety and efficacy in treating inhibitor patients has opened new possibilities for addressing severe arthropathy with flexion contracture. This case report demonstrates that the use of rFVIIa in such a situation must include dosing flexibility that is both patient-specific and related to the potential for bleeding; the ability to maintain clinical haemostasis with a prophylactic dose of rFVIIa given as little as once daily; and the capacity for higher doses of rFVIIa, particularly in children because their kinetic profiles differ from adults.

Levels of racism: a theoretic framework and a gardener's tale

The author presents a theoretic framework for understanding racism on 3 levels: institutionalized, personally mediated, and internalized. This framework is useful for raising new hypotheses about the basis of race-associated differences in health outcomes, as well as for designing effective interventions to eliminate those differences. She then presents an allegory about a gardener with 2 flower boxes, rich and poor soil, and red and pink flowers. This allegory illustrates the relationship between the 3 levels of racism and may guide our thinking about how to intervene to mitigate the impacts of racism on health. It may also serve as a tool for starting a national conversation on racism.

Disparities in health: common myths and uncommon truths

A reappraisal of disparities by deprivation provides new and important information. NZDep96 is an area-based index of socioeconomic deprivation that uses nine variables measured in the 1996 census. The distribution of the Māori ethnic group is sharply skewed towards the most deprived deciles with only three percent in decile 1 and twenty-six percent residing in decile 10 meshblocks. More than half (56%) of Māori live in areas represented by the three most deprived deciles. This pattern is consistent within both sectors of the Māori ethnic group: sole Māori--those who give Māori as their only ethnicity and mixed Māori--those who give Māori as only one of their ethnicities. This is a 'distribution gap'. Within disparities analysis, there is also evidence of an 'outcome gap'. That is, the health outcomes of Māori are different from non-Māori, even after controlling for deprivation. For example, overseas data on life expectancy at birth have demonstrated social class gradients with lower life expectancy among manual workers and increasing life expectancy for trades-people, through to managerial and professional workers. This gradient is also evident in Aotearoa with life expectancy at birth decreasing as deprivation increases. A third dimension is evident in a review of disparities by deprivation,--a 'gradient gap'. This describes the relationship between ethnicity and increasing deprivation. It is as if the effect of increasing deprivation compounds risk for Māori whereas Pākehā do not seem subject to this effect. Analyses that foreground disparities have been portrayed as oppositional or secondary to Māori health development. In such frameworks where a disparity focus intersects with a development focus, the impression is given that the two are interconnected but move past each other in different directions. Our analysis promotes the disparities focus and the development focus as parallel reinforcing variables, each informing the other in the design and provision of services that have as their starting point, Māori needs. These services offer hope and opportunity for Māori but risk the vulnerability of special provision services (e.g. cuts in government expenditure). Furthermore the may delay the imperative of addressing the societal drivers that perpetuate disparities. This tension to engage in remedial reform is an important dilemma in Māori health development.

The effect of devices used to reduce the risk of blood spillage or needlestick injury on the flow of intravenous infusion systems

We evaluated the effect of two devices used to reduce needlestick injury and blood spillage on the flow of saline, polygeline and blood through intravenous infusion equipment and their effects on methods of increasing flow. The devices studied all reduced flow compared with control. The reductions were less for the reflux valve (< or = 9%) and greater for the anaesthesia extension set (< or = 59%), with little further reduction in flow when both were used in series (< or = 60%). Reductions in flow increased with increasing viscosity of the fluid infused, being greatest with blood. The flow reduction produced by the reflux valve was more than compensated by increasing pressure or increasing to the next larger cannula size. The flow reduction produced by the anaesthesia extension was compensated by increasing pressure but not by increasing cannula size.

Can behavioral risk factors explain the difference in body mass index between African-American and European-American women?

African-American women are heavier than European-American women; the reasons are unknown. The purpose of this study was to examine potentially modifiable reasons for the weight difference among 86,326 female nurses. The determinants of body mass index (BMI) were modelled using the method of linear regression. The findings included the following: mean BMI (kg/m2) was 9.0% (95% CI, 7.8-10.1%) higher among African American (27.3) than among European-American women (25.1) (P<0.0001). However, recalled BMI at age 18 was equal in the two groups (21.4, P=0.98). Multivariate determinants of BMI include age, age 18 BMI, alcohol and calorie intake, exercise, marital status, parity, race, recent intentional weight loss, smoking, and television watching. Even after controlling for these factors, African-American women still had an 8.6% (95% CI, 7.7-9.5%) higher BMI than European-American women. Correction for error in measurement of physical activity attenuated this difference to 6.4% (95% CI, 5.0-7.8%). In conclusion, in this single occupation group, African-American women had a significantly higher BMI than European-American women. Age and measured behavioral factors did not explain this difference. However, imprecision in the measurement of diet and activity may explain this difference in part. Better measurement may help quantify the differences that are as yet unexplained.

Serum creatinine levels in the US population: third National Health and Nutrition Examination Survey

This report describes the distribution of serum creatinine levels by sex, age, and ethnic group in a representative sample of the US population. Serum creatinine level was evaluated in the third National Health and Nutrition Examination Survey (NHANES III) in 18,723 participants aged 12 years and older who were examined between 1988 and 1994. Differences in mean serum creatinine levels were compared for subgroups defined by sex, age, and ethnicity (non-Hispanic white, non-Hispanic black, and Mexican-American). The mean serum creatinine value was 0.96 mg/dL for women in the United States and 1.16 mg/dL for men. Overall mean creatinine levels were highest in non-Hispanic blacks (women, 1.01 mg/dL; men, 1.25 mg/dL), lower in non-Hispanic whites (women, 0.97 mg/dL; men, 1.16 mg/dL), and lowest in Mexican-Americans (women, 0.86 mg/dL; men, 1.07 mg/dL). Mean serum creatinine levels increased with age among both men and women in all three ethnic groups, with total US mean levels ranging from 0.88 to 1.10 mg/dL in women and 1.00 to 1.29 mg/dL in men. The highest mean creatinine level was seen in non-Hispanic black men aged 60+ years. In the total US population, creatinine levels of 1.5 mg/dL or greater were seen in 9.74% of men and 1.78% of women. Overall, among the US noninstitutionalized population, 10.9 million people are estimated to have creatinine values of 1.5 mg/dL or greater, 3.0 million have values of 1.7 mg/dL or greater, and 0.8 million have serum creatinine levels of 2.0 mg/dL or greater. Mean serum creatinine values are higher in men, non-Hispanic blacks, and older persons and are lower in Mexican-Americans. In the absence of information on glomerular filtration rate (GFR) or lean body mass, it is not clear to what extent the variability by sex, ethnicity, and age reflects normal physiological differences rather than the presence of kidney disease. Until this information is known, the use of a single cutpoint to define elevated serum creatinine values may be misleading.

Living beyond our "means": new methods for comparing distributions

This paper introduces the projection methods for describing and testing the differences between pairs of continuous distributions. These methods include the projection plot, the projection spline, and the iter-1 test. The projection plot displays the difference between corresponding quantiles against the average of the corresponding quantiles. It is analogous to an empirical quantile-quantile plot that has been rotated 45 degrees. The projection spline is a knotted linear spline iteratively fit to the projection plot so that all knots are associated with significant changes in slope. It summarizes nonrandom deviations from linearity on the projection plot, allowing classification of the highest level of difference between two distributions as a difference in shape, in spread, or in location. The iter-1 test compares the first iteration of the projection spline with the line y = 0, providing a global test of difference between two distributions that is more powerful in simulations than either the chi-square test of independence or the Kolmogorov-Smirnov test. These methods will enhance epidemiologic practice by making the comparison of full distributions an accessible tool for routine data analysis.

Use of randomly amplified polymorphic DNA markers for the genetic analysis of relatedness and diversity in chickens and turkeys

A study involving the use of random amplified polymorphic DNA (RAPD) was conducted to evaluate genetic polymorphism and relatedness within and among four chicken breeds: Araucona, Rhode Island Red, White Leghorn, and White Plymouth Rock, and two turkey populations, a long-term randombred and a commercial strain. A total of 60 random primers were used in the RAPD analyses. Forty-two of the 60 primers tested amplified patterns with at least one polymorphic fragment in one or more of the populations. Six of these 42 primers amplified polymorphic fragments in each of the six strains with a within- and between-population average band-sharing frequency of less than one but above zero (P < 0.05). Differences among the six primers for genetic distance (D) among populations were significant (P < 0.05). A consensus dendogram was therefore developed to show the phylogenetic relationships among the populations. As expected, estimates of D between populations were lowest within species and highest between species. The results provide evidence of the applicability of RAPD to determining genetic relatedness within and among different poultry populations and in developing reproducible markers useful in evaluating individual variation in chickens and turkeys.

Detailed physical map of human chromosomal region 11q12-13 shows high meiotic recombination rate around the MEN1 locus

We have constructed a physical map of the region q12-13 on chromosome 11 by combining data generated from a panel of radiation-reduced somatic cell hybrids and pulsed-field gel electrophoresis (PFGE). Twenty different genetic markers have been sublocalized and ordered within this region and a total of 8.0 megabases has been mapped in detail using rare-cutting restriction endonucleases and PFGE. In two instances, the long-range restriction PFGE map spans the total distance between pairs of loci that have been previously mapped by genetic linkage in reference families. Comparison of this physical map with the available linkage map indicates a great variation in the recombination frequency over the region. The recombination rate is higher than expected, particularly for markers flanking the MEN1 region. Thus, for the closest pair of linked markers on the centromeric side, one centimorgan corresponds to approximately 300 kilobases, and for markers on the telomeric side, one centimorgan corresponds to approximately 350-600 kilobases.

"Race" in the epidemiologic literature: an examination of the American Journal of Epidemiology, 1921-1990

The routine presentation of epidemiologic data by "race" has been challenged as impeding identification of modifiable risk factors and fostering an unsubstantiated belief in the biologic distinctness of the "races." This study examines the past and current uses of "race" in US epidemiologic research. The authors reviewed every paper published in the 1921, 1930, 1940, 1950, and 1960 volumes of the American Journal of Hygiene and in the 1965, 1970, 1975, 1980, 1985, and 1990 volumes of the American Journal of Epidemiology. Of the total of 1,200 papers published during the sample years, 558 reports of original epidemiologic research conducted in the United States were identified. The proportion of these papers containing a reference to "race" rose steadily from 1975. However, the proportion of papers reporting inclusion of "nonwhite" populations did not show a parallel increase. Exclusion of "nonwhite" subjects and description of predominantly "white" study populations increased instead. Recommendations for future epidemiologic practice include the following: 1) greater inclusion of "nonwhite" populations in epidemiologic research and 2) vigorous investigation of the root causes of observed "race"-associated differences.

Hexamethylmelamine chemotherapy for persistent or recurrent epithelial ovarian cancer

The purpose of this study was to determine the activity and toxicity of hexamethylmelamine chemotherapy in patients with persistent or recurrent epithelial ovarian cancer. Forty-nine women received hexamethylmelamine 100 to 150 mg/day for 14 days, repeated at 4-week intervals. All patients had previously received at least one chemotherapy regimen, and 46 (94%) had received cisplatin. Among 25 patients with clinically measurable disease there were three complete and two partial responses, for an objective response rate of 20%. The mean progression-free interval for responders was 38.6 months versus 9.6 months for nonresponders or patients with nonmeasurable disease (p less than 0.001). Thirteen patients are alive, eight with no clinical evidence for disease. Only four patients discontinued therapy because of toxic reactions. Hexamethylmelamine appears to be a well-tolerated drug with activity against ovarian cancer previously treated with cisplatin.

Calin--a platelet adhesion inhibitor from the saliva of the medicinal leech

The saliva of the medicinal leech, Hirudo medicinalis, contains a potent, hitherto unsuspected, inhibitor of collagen-mediated platelet adhesion/aggregation. Calin, of molecular size approximately 65,000 (reduced), has a rapid (1-10 min) effect on collagen which is reflected in its ability to suppress collagen-induced platelet aggregation, as well as adhesion of platelets to collagen-coated microcarrier beads. It also causes flocculation of Type I collagen fibril suspensions. Calin is differentiated from leech collagenase in two ways: (1) by demonstrating, by SDS-PAGE analysis of the products of incubations of Calin with Type I collagen at 37 degrees C, that Calin binds to but does not cleave collagen; and (2) by showing that Calin cannot be purified using the methods used to isolate leech collagenase. Calin's rapid and unusual interaction with collagen makes it a prime candidate for one of the agents that are the causative factors of the prolonged bleeding phenomenon seen after leech bites.

The biological function of hementin in the proboscis of the leech Haementeria ghilianii

The giant Amazon leech Haementeria ghilianii feeds by inserting an exceedingly long tubular proboscis (up to 10 cm) deep into its mammalian host. The wound from its bite is not associated with prolonged bleeding because all antihaemostatic factors, including the fibrinogenolytic enzyme hementin, appear to be secreted exclusively into the lumen of the proboscis. It is in this narrow lumen that blood first comes into contact with hementin, the secretion of which is under neuronal control from the brain. During feeding, about 15 ml of blood are sucked through the proboscis at the rate of approximately 0.14 ml/min. A complete passage of blood takes less than 1 min, much faster than the approximately 6 min needed for coagulation (fibrin formation). Therefore, it is unlikely that hementin functions in the proboscis simply to prevent fibrin formation. Of greater risk is platelet aggregation which can occur within 1-2 min. The formation of a platelet-rich clot within the proboscis could make the proboscis non-functional. Hementin's unique ability to dissolve platelet-rich clots offers a way of restoring blood flow through the proboscis. Hementin is able to disaggregate platelets by breaking the fibrinogen crosslink between platelets. Hementin's unique cleavage site in the connector region of platelet-bound fibrinogen is thought to be a most effective mechanism for eliminating the crosslinking.

Isolation of thrombin inhibitor from the leech Hirudinaria manillensis

The leech Hirudinaria manillensis belongs to the same family as the medicinal leech Hirudo medicinalis, which has been widely used for the study of hirudin, a specific thrombin inhibitor. A similar inhibitor has now been isolated from the heads of the Hirudinaria leech by acetone/acid extraction and further purified to near homogeneity by ion exchange chromatography followed by affinity chromatography on thrombin-agarose and reverse phase HPLC. The purified material was recovered at about 10-15% yield and had a specific activity of about 12,000-14,000 ATU/mg, similar to other hirudin variants. The inhibitor was shown to be homogenous by sodium dodecyl sulphate/polyacrylamide gel electrophoresis in the presence of 8 M urea with an apparent molecular mass of about 7000 daltons under reducing conditions. Comparison of the anticoagulant effect on human plasma by partial thromboplastin time assay have shown that the inhibitor from Hirudinaria has similar potency as hirudin variant 1 at equivalent dosage. However, it does not cross-react with monoclonal antibodies towards recombinant hirudin variant 1. Comparison of the N-terminal amino acid sequence up to residue 25 also indicates differences at positions 2, 13, 17 and 24 between the two thrombin inhibitors. These findings indicate that the primary anticoagulant present in the leech Hirudinaria is a potent thrombin inhibitor (Bufrudin) with biological activity similar to hirudin, but differs in its structural and immunological properties.