Venous thromboembolism incidence and risk factors in adults with acute lymphoblastic leukemia treated with and without pegylated E. coli asparaginase-containing regimens.

PURPOSE: Asparaginases, key agents in treatment of acute lymphoblastic leukemia (ALL), are associated with venous thromboembolism (VTE). While risks of short-acting asparaginase-related VTE is well-known, we studied VTE incidence and risk factors in adult ALL patients treated with and without long-acting pegylated asparaginase (PegA). METHODS: Single-center, retrospective analysis of 89 ALL patients treated with (n = 61) or without (n = 28) PegA at Greenebaum Comprehensive Cancer Center. Reviewed patient and disease characteristics, treatment, and VTE incidence. RESULTS: VTE during treatment occurred in 31 patients (35%), and was associated with PegA (p = 0.001) and Philadelphia chromosome negativity (p = 0.002). Among PegA recipients, VTE was associated with a significantly higher mean body mass index (BMI) of 31.3 kg/m2 (p = 0.037), and was more common with pre-T/T cell compared to pre-B/B cell ALL (68.2% vs. 33.3%, p = 0.009). Antithrombin-III (ATIII) levels were measured for 26 patients; 16 (61.5%) were < 50%. Of those, 8 (50%) experienced VTE, while 3 of 10 (30%) patients with ATIII levels ≥ 50% experienced VTE. VTE occurred in 7 of 13 (54%) of patients who received ATIII repletion. There was a trend toward a higher incidence of VTE in the PegA group among patients with non-O compared to O blood type (55.9% vs. 33.3%, p = 0.079) as well as those with a higher hemoglobin at diagnosis (9.3 vs 8.1 g/dL, p = 0.056). CONCLUSION: This study confirms PegA as a risk factor for VTE in patients with ALL. Risk factors among those receiving PegA include higher BMI and pre-T/T cell ALL. ATIII repletion was not shown to be protective against VTE. There was a higher incidence of VTE in patients who received PegA with non-O compared to O blood type, but the precise correlation is uncertain.

Evening primrose oil or forskolin ameliorates celecoxib-enhanced upregulation of tissue factor expression in mice subjected to lipopolysaccharide-induced endotoxemia.

Celecoxib, a selective cyclooxygenase-2 inhibitor, produces thrombotic events in patients predisposed to cardiovascular risk factors. One theory reported an increase in endothelial expression of tissue factor (TF) as a predisposing factor. This work explored the effect of evening primrose oil (EPO), a source of prostaglandin E1, and forskolin (a cyclic adenosine monophosphate stimulator) against the prothrombotic effect of celecoxib in mice. Lipopolysaccharide mouse model of endotoxemia was used to induce an upregulation of TF activity. Male mice received celecoxib (25 mg/kg), celecoxib plus EPO, or celecoxib plus forskolin for 4 weeks and then subjected to a prothrombotic challenge in the form of an intraperitoneal injection of lipopolysaccharide. Results showed an increase in plasma TF activity, endothelial TF expression, and thrombin-antithrombin (TAT) but lower antithrombin III (ATIII) level in mice that received celecoxib in comparison to those that received the vehicle. Adding EPO or forskolin to celecoxib regimen significantly decreased the prothrombotic effect of celecoxib. A positive correlation (r = 0.8501) was found between TF activity and TAT. Co-administration of EPO or forskolin decreased the activity of TF and mitigated the prothrombotic effect of celecoxib. Therefore, these combinations may have the utility to abrogate the prothrombotic adverse effect of celecoxib in clinical setting.

Synthesis and Evaluation of a Series of Long-Acting Glucagon-Like Peptide-1 (GLP-1) Pentasaccharide Conjugates for the Treatment of Type†2 Diabetes.

The present study details the development of a family of novel D-Ala(8) glucagon-like peptide-1 (GLP-1) peptide conjugates by site specific conjugation to an antithrombin III (ATIII) binding carrier pentasaccharide through tetraethylene glycol linkers. All conjugates were found to possess potent insulin-releasing activity. Peptides with short linkers (<25 atoms) conjugated at Lys(34) and Lys(37) displayed strong GLP-1 receptor (GLP-1-R) binding affinity. All D-Ala(8) GLP-1 conjugates exhibited prominent glucose-lowering action. Biological activity of the Lys(37) short-linker peptide was evident up to 72 h post-injection. In agreement, the pharmacokinetic profile of this conjugate (t1/2 , 11 h) was superior to that of the GLP-1-R agonist, exenatide. Once-daily injection of the Lys(37) short-linker peptide in ob/ob mice for 21 days significantly decreased food intake and improved HbA1c and glucose tolerance. Islet size was decreased, with no discernible change in islet number. The beneficial effects of the Lys(37) short-linker peptide were similar to or better than either exenatide or liraglutide, another GLP-1-R agonist. In conclusion, GLP-1 peptides conjugated to an ATIII binding carrier pentasaccharide have a substantially prolonged bioactive profile compatible for possible once-weekly treatment of type 2 diabetes in humans.

Efficacy of argatroban in critically ill patients with heparin resistance: a retrospective analysis.

The patients who do not respond even to very high dosages of heparin are assumed to suffer from heparin resistance. The aim of this study was to investigate whether critically ill patients suffering from heparin resistance generally have low antithrombin III (AT) levels, and if the direct thrombin inhibitor argatroban in that case can be an effective option to achieve prophylactic anticoagulation. The study was conducted at the Department for General and Surgical Intensive Care Medicine at the University Hospital Innsbruck. We retrospectively included all patients between 2008 and 2012, who received argatroban because of poor response to high-dosage heparin prophylaxis. The period under observation lasted in total for 9 days, 2 days of anticoagulation with unfractionated heparin (UFH) and 7 days with argatroban. The primary objective was to investigate if after 7 (± 1) hours of switching to argatroban the activated partial thromboplastin time (aPTT) levels were in a prophylactic range of 45 to 55 seconds. Further objectives were to assess the AT level, side effects such as bleeding or thromboembolism, platelet count, correlation between organ function and argatroban dose as well as any need for allogeneic blood products. The study population, consisting of 5 women and 15 men with a mean (± standard deviation, SD) age of 54.6 ± 16.3 years, differed in many clinical aspects. A median (interquartile range) heparin dose of 1,000, 819 to 1,125 IU/h was administered for 2 days and failed in providing a prophylactic anticoagulation measured by the aPTT. The mean aPTT level with heparin treatment was 38.5 seconds (± 4.7) its change within that period was not significant. After switching to argatroban, the mean increase of the aPTT levels in all study patients amounted from 38.5 to 48.3 seconds (p < 0.001). The rise in aPTT clearly reaches sufficient prophylactic anticoagulant levels. The maintenance of prophylactic aPTT levels was achieved over the period of 1 week. There was neither a correlation found between low-AT levels and occurrence of heparin resistance, nor between the simplified acute physiology score II and the administered argatroban dose (r = -0.224, p = 0.342). The results of the present study indicate that argatroban is an effective alternative therapy, especially in critically ill patients, to achieve prophylactic anticoagulation when heparin resistance occurs.

Moutan cortex radicis improves lipopolysaccharide-induced acute lung injury in rats through anti-inflammation.

Moutan cortex radicis (MCR) is a Chinese herbal medicine that was widely used over a long period as an analgesic, antipyretic, and anti-inflammatory agent in China. Lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rat models is considered similar to adult respiratory distress syndrome (ARDS) in humans. Therefore, the present study investigates the effect of MCR on ALI. The ALI model was developed through the intra-tracheal (IT) administration of LPS (16mg/kg) to Sprague-Dawley (SD) rats, which formed the LPS group. MCR was orally administered before and after LPS was introduced into rats (MCR-LPS group and LPS-MCR group, respectively). In the MCR-LPS group, rats received MCR 2g/kg/times 3 times before LPS challenge; the LPS-MCR group received MCR 2g/kg/times 3 times after LPS challenge. The results of this experiment indicate that the number of total cells and neutrophils and the concentration of protein exudation in bronchoalveolar lavage fluid (BALF) significantly decreased in the MCR-LPS group. Cytokine levels, including levels of interleukin (IL)-1ß, macrophage-inflammatory peptide (MIP)-2, IL-6, and IL-10, in BALF were also significantly inhibited at 16h after LPS administration in the MCR-LPS group. Myeloperoxidase (MPO) activity in lung tissue was reduced in the MCR-LPS and LPS-MCR groups at 16h after LPS administration. Furthermore, leukocyte infiltration and protein exudation in the alveolar space were less severe in the MCR-LPS group than in the LPS group. Therefore, the findings of this study suggest that the administration of MCR prior to LPS improves ALI, possibly mediating ALI through anti-inflammation.

[Analysis of thrombin-antithrombin complex expressions in the plasma and the hematoma fluid of intracerebral hemorrhage patients of excess syndrome of stroke and depletion syndrome of stroke].

OBJECTIVE: To study the relationship between the expressions of thrombin-antithrombin (TAT) complex and excess syndrome of stroke (ESS) and depletion syndrome of stroke (DSS) by dynamically observing the expressions of TAT complex in the plasma and hematoma fluid of intracerebral hemorrhage (ICH) patients. METHODS: Sixty patients were assigned to three groups according to syndrome typing, i.e., as yang excess group (18 cases), yin excess group (22 cases), and depletion syndrome group (20 cases). The hemorrhage volume was assessed. NIHSS and GCS were scored. Besides, 30 healthy volunteers at the Physical Examination Center, Second People's Hospital Affiliated to Fujian University of Traditional Chinese Medicine were recruited as the normal control group. Another 10 patients in need of lumbal anesthesia were recruited as the cerebrospinal fluid control group, who suffered from surgical, gynecologic pelvic diseases, or diseases from lower limbs, but unaccompanied with cardio-/cerebrovascular diseases. The expressions of TAT complex were detected in the venous blood and hematoma fluid of the patient groups and in the venous blood or the cerebrospinal fluid of the control group using ELISA. RESULTS: The syndromes were sequenced as the depletion syndrome > the yin excess syndrome > the yang excess syndrome according to the hemorrhage volume and NIHSS score. They were sequenced as the yang excess syndrome > the yin excess syndrome >the depletion syndrome according to the GCS score. The plasma TAT complex content on the 4th day in the ICH group was lower than that at the rest time points, showing statistical significance (P<0.01). Compared with the normal control group, the plasma TAT complex on the 1st, 2nd, and 4th day all increased with statistical difference (P<0.01). Statistical significance of the TAT complex in the hematoma fluid of the ICH group existed when compared it on the 1st, 2nd, and 4th day (P<0.01). Compared with the cerebrospinal fluid control group, the contents of the TAT complex in the hematoma fluid of the ICH group increased with statistical difference (P<0.01). The hemorrhage volume of ICH patients was positively correlated with NIHSS (r=0.809, P<0.01) and negatively correlated with GCS (r=-0.833, P<0.01). The TAT complex was obviously higher in the ICH group than in the two control groups in a dynamic way (P<0.01). There was obvious difference in the expressions of TAT among yang excess group, yin excess group, and depletion syndrome group (P<0.01). The expressions of TAT in the plasma and the hematoma fluid of the ICH group were negatively correlated with GCS score and positively correlated with NIHSS score (both P<0.01). CONCLUSIONS: TAT complex participated in secondary neuron injury after ICH, which could be taken as an objective index for clinical observation. It also could provide evidence for syndrome quantification of excess syndrome and depletion syndrome.

[Changes in plasma hemostatic parameters under intravascular laser irradiation of blood in patients with community-acquired pneumonia].

AIM: To study the time course of changes in the activity of the protein C system and other hemostatic parameters under intravascular laser irradiation of blood (ILIB) in patients with community-acquired pneumonia (CAP). SUBJECTS AND METHODS: One hundred and forty patients aged 17 to 62 years (mean 39.5 +/- 8.4 years) with CAP were examined. A control group (n = 40) received conventional drug therapy; the study group (n = 100) had a course of ILIB in addition to conventional therapy. RESULTS: Before treatment, the patients with CAP were observed to have a lower protein C system activity and the signs of hypercoagulation that were eliminated by ILIB. CONCLUSION: ILIB is an effective method in correcting hemocoagulative disorders in patients with CAP.

Lower-extremity functional electrical stimulation decreases platelet aggregation and blood coagulation in persons with chronic spinal cord injury: a pilot study.

BACKGROUND: Individuals with spinal cord injury (SCI) develop premature cardiovascular disease. Regular exercise reduces the incidence and symptoms of cardiovascular disease in able-bodied individuals; these salutary effects of exercise have not been documented in persons with SCI. OBJECTIVE: To evaluate the effects of functional electrical stimulation leg cycle ergometry (FES-LCE) exercise training on platelet aggregation and blood coagulation in persons with SCI. PARTICIPANTS: Subjects (n=14) with stable chronic (>1 year) paraplegia (T1-T10) or tetraplegia (C4-C8). METHODS: Blood samples were collected before and after the first and eighth sessions (2 sessions per week for 4 weeks) of FES exercise. RESULTS: Platelet aggregation was inhibited by 20% after the first session and by 40% (P < 0.001) after the eighth session. Thrombin activity was unchanged after the first session (10.7 +/- 0.85 s to 10.43 +/- 0.56 s) and decreased after the eighth session (12.5 +/- 1.98 s to 11.1 +/- 1.7 s; P < 0.0003). Antithrombin III activity increased after the first (103.8% +/- 8.9% to 110% +/- 6.9%; P < 0.0008) and eighth sessions (107.8% +/- 12.1% to 120.4% +/- 13.1%; P < 0.0001). Cyclic adenosine monophosphate increased after the first (9.9% + 2.5% to 15.8% +/- 3%; P < 0.001) and eighth sessions (17.8% +/- 4.2% to 36.5% +/- 7.6%; P < 0.0001). After the eighth session, factors V and X increased significantly (88% +/- 27% to 103% +/- 23%, P < 0.0001; 100% +/- 40% to 105% +/- 7%, P < 0.01, respectively); factors VII and VIII and fibrinogen did not change significantly. A significant reduction in platelet activation/aggregation was demonstrated in response to FES-LCE. The decrease in thrombin level was caused by the simultaneous increase in antithrombin activity. CONCLUSION: These findings provide new insight into the potential protective effects of FES-LCE against the risk of cardiovascular disease.

Development of idraparinux and idrabiotaparinux for anticoagulant therapy.

Idraparinux is an analogue of fondaparinux binding with high affinity to antithrombin. It was designed for weekly, rather than daily, administration, with an exceptionally long half-life. One potential problem with small heparin-like fragments of this type is the difficulty of neutralising excessive activity in the case of side-effects or overdose. The efficacy of idraparinux was was proven in clinical studies with patients suffering from venous thromboembolism (VTE) or atrial fibrillation. Due to major bleeding events during treatment for more than six months the development of idraparinux was stopped. Idrabiotaparinux has an attached biotin moiety at the non-reducing end unit, which allows its neutralisation with avidin, an egg-derived protein with low antigenicity. This compound is currently investigated in clinical trials for prevention of recurrent VTE in patients with acute pulmonary embolism. The future of idrabiotaparinux depends also on the safety and efficacy of avidin.

Design of novel aminopyrrolidine factor Xa inhibitors from a screening hit.

Starting from a hit identified by focused screening, 3-aminopyrrolidine factor Xa inhibitors were designed. The binding mode as determined by X-ray structural analysis as well as the pharmacokinetic behaviour of selected compounds is discussed.

Hemocompatibility of high strength oxide ceramic materials: an in vitro study.

High strength oxide ceramic materials like alumina and zirconia are frequently used for artificial joints because of their biocompatibility and high wear resistance. Their suitability as materials for implants and biomedical devices with direct blood contact, such as cardiovascular implants or components for blood pumps and dialyzers, has not been confirmed to date. The objective of this study was to investigate whether oxide ceramics show sufficient hemocompatibility. Dense specimens were made out of alumina, zirconia, titanium oxide, and aluminum titanate. Polyvinylchloride and silicone were additionally tested as reference materials. Interactions of human blood with the surfaces were studied by investigating partial thromboplastin time (PTT), thrombin antithrombin III complex (TAT), free plasma hemoglobin concentration, complete blood count, complement factor 5a, and protein adsorption. The results from the PTT and TAT tests clearly indicated higher blood activation by the ceramic materials when compared to the two polymer materials. However, alumina and zirconia showed lower C5a concentrations and less protein adsorption than the reference materials. Our results revealed that oxide ceramic materials alone cannot be used for implants in direct blood contact without modification of the ceramic surface, for example, by made-to-measure inert nanocoatings.

Heparin binds to lipopolysaccharide (LPS)-binding protein, facilitates the transfer of LPS to CD14, and enhances LPS-induced activation of peripheral blood monocytes.

Heparin is one of the most effective drugs for preventing and treating thromboembolic complications in surgical patients. Recent evidence suggests that heparin enhances the proinflammatory responses of human peripheral blood monocytes to Gram-negative endotoxin (LPS). We have identified LPS-binding protein (LBP) as a novel heparin-binding plasma protein. The affinity of LPB to heparin was KD = 55 +/- 8 nM, as measured by surface plasmon resonance. Using a fluorescence-based assay, we showed that clinically used heparin preparations significantly enhance the ability of LBP to catalytically disaggregate and transfer LPS to CD14, the LPS receptor. The presence of clinically relevant heparin concentrations in human whole blood increased LPS-induced production of the proinflammatory cytokine IL-8. Fondaparinux, which is identical with the antithrombin III-binding pentasaccharide in heparin, did not bind to LBP or alter LBP function. Thus, this novel anticoagulant drug is a potential candidate for safe administration to patients who have endotoxemia and require anticoagulation.

Activation of blood coagulation in patients undergoing postoperative blood salvage and re-infusion of unwashed whole blood after total knee arthroplasty.

BACKGROUND: Perioperative blood salvage is commonly used in cardiovascular surgery and has been more recently introduced in major orthopedic surgery. Limited information is available on the influence of re-infused whole blood on the hemostatic system in orthopedic patients. MATERIALS AND METHODS: The aim of this study was to assess whether perioperative salvage and re-infusion of unwashed whole blood is associated with an activation of blood coagulation in patients undergoing total knee replacement. Consecutive patients receiving re-infusion were included in the study (n=13). Patients undergoing total knee replacement without perioperative blood salvage and re-infusion served as controls (n=6). In patients receiving re-infusion thrombin-antithrombin complexes (TAT), plasmin-antiplasmin complexes (PAP) and fibrinogen were assayed at the following times: before surgery (baseline), immediately before re-infusion (T0), immediately (T1), 2 h (T2) and 24 h (T3) after the end of re-infusion. In control patients blood samples were drawn at the average times corresponding to each of the sampling time in the patients receiving re-infusion. The first post-surgery LMWH dose was given within 12 h after surgery. RESULTS: TAT and PAP increased after surgery both in patients receiving re-infusion and controls. An increase of TAT and PAP was observed immediately after re-infusion with respect to baseline (TAT 513.1 +/- 259.1 microg/l vs. 5.3 +/- 4.9, p<0.0001; PAP 7408.0 +/- 1892.1 microg/l vs. 461.4 +/- 217.1, p<0.0001) and to controls (TAT 60.4 +/- 26.9 microg/l, p=0.002; PAP 2208.3 +/- 1446.4 microg/l, p<0.001). The levels of TAT and PAP in patients receiving re-infusion remained high at 2 h after re-infusion compared to those of the controls (TAT 124.1 +/- 38.3 microg/l vs. 38.08 +/- 18.9, p=0.016; PAP 5690.7 +/- 1435.5 microg/l vs. 1613.9 +/- 706.0, p<0.001) and decreased 24 h thereafter. Fibrinogen level was lower in patients receiving re-infusion compared to controls. CONCLUSIONS: Whole blood re-infusion is associated with an activation of blood coagulation in patients undergoing total knee replacement. The clinical relevance of this activation has to be tested in prospective studies with adequate sample size.

Increase of anti-metastatic efficacy by selectivity- but not affinity-optimization of synthetic serine protease inhibitors.

Although tumors frequently show elevated protease activities, the concept of anti-proteolytic cancer therapy has lost momentum after failure of clinical trials with broad-spectrum matrix metalloproteinase inhibitors. Thus we need to adapt our design strategies for protease inhibitors. Here, we employed a series of seven structurally fine-modulated and pharmacokinetically closely related synthetic 4-amidinobenzylamine-based inhibitors with distinct selectivity for prototypical serine proteases in a murine T cell lymphoma liver metastasis model. This in vivo screening revealed efficacy of urokinase inhibitors but no correlation between urokinase selectivity or affinity and anti-metastatic effect. In contrast, factor Xa-selective inhibitors were more potent, demonstrating factor Xa or a factor Xa-like serine protease likely to be more determinant in this model. Factor Xa selectivity, but not affinity, significantly improved anti-metastatic efficacy. For example, factor Xa inhibitors CJ-504 and CJ-510 exert similar affinity for factor Xa (K(i)=14 nM versus 8.8 nM) but CJ-504 was 70-fold more selective for factor Xa. This correlated with higher anti-metastatic efficacy (58.8% with CJ-504; 28.2% with CJ-510). Our results show that among the protease inhibitors employed that have affinities in the nanomolar range, the strategy of selectivity-optimization is superior to further improvement of affinity to significantly enhance anti-metastatic efficacy. This appreciation may be important for the future rational design of new anti-proteolytic agents for cancer therapy.

The botanical extracts of Achyrocline satureoides and Ilex paraguariensis prevent methylglyoxal-induced inhibition of plasminogen and antithrombin III.

Endogenously produced dicarbonyls, such as methylglyoxal (MG), are involved in advanced glycation end-product formation and thus linked to the pathophysiology of diabetic chronic complications. While the search for synthetic new antiglycation agents continues, little attention has been paid to putative antiglycation agents in natural compounds. Given the link between glycation and oxidation, in this work, we study the effects of methylglyoxal on two model systems; plasminogen and antithrombin III (AT III), then we set out to unravel a possible antiglycation effect for extracts of the flavonoid-rich common herbal species Achyrocline satureoides (AS) and Ilex paraguariensis (IP). Using SAR-PRO-ARG-pNA as a specific thrombin substrate, we show that incubation of plasma with MG decreases heparin activation of AT III by up to a 70%, in a dose-dependent manner. A parallel dose-dependent decrease in plasminogen activity reaching more than 50% was shown using D-BUT-CHT-lys-pNA as a plasmin-specific substrate. Extracts of AS and IP display a dose dependent inhibition of the action of the dicarbonyl, already significant at a 1/100 dilution of the herbal infusions. The inhibition was comparable to that obtained by using millimolar concentrations of known AGE inhibitors such as aminoguanidine and carnosine as well as micromolar concentrations of the antioxidant ascorbic acid. We believe our system of whole plasma glycation over 16 h with micromolar concentrations of MG, coupled with the measurement of activities of plasminogen and AT III by specific substrates provides a straightforward, practical method for monitoring the action of putative antiglycation agents. If predictably milder glycated forms of AT III and plasminogen were to be secreted in vivo, the loss of activities shown here could act synergistically to generate hyperthrombicity.

Effect of new synthetic heparin mimetics on whole blood thrombin generation in vivo and in vitro in rats.

The effect of new heparin mimetics (synthetic oligosaccharides) was studied in vitro with regard to thrombin generation (TG) in rat platelet rich plasma (PRP) and whole blood (WB) and in vivo on stasis-induced venous thrombosis in the rat. TG in PRP and in WB was highly dependent on platelet count and strongly influenced by the haematocrit. The peak of TG appeared to be significantly higher in WB than in PRP whereas the endogenous thrombin potential (ETP) was not significantly different under either condition. The effect of hirudin, the synthetic pentasaccharide SR90107/Org31540 (SP) and heparin were measured on TG in PRP and WB. We then compared the effect of two new synthetic heparin mimetics (SR121903A and SanOrg123781) with potent and comparable antithrombin (AT) mediated activity against factor Xa and thrombin. These two compounds were made of a pentasaccharide with a high affinity to AT, prolonged at the non-reducing end by an oligosaccharide chain recognised by thrombin. In SR121903A, the charge density and charge distribution was analogous to that of heparin whereas in SanOrg123781 the charges were only located on the last 5 saccharides of the non-reducing end of the molecule. In PRP and in WB, SR121903A acted on the lag time and on the AUC whereas SanOrg123781 inhibited thrombin formation with no effect on the lag time. SanOrg123781 was more potent in inhibiting TG than SR121903A. This difference was due to the structures of the compounds that differed in their ability to be neutralised by platelet factor 4. The antithrombotic effect of the two compounds was examined in a venous thrombosis model in rats. We observed that SanOrg123781 was more active than SR121903A and heparin. Taken together, these results indicate that the activity of oligosaccharides is greatly influenced by the global charge density of the molecule and show that SanOrg123781 is a potent and promising antithrombotic drug candidate.

Proteinase inhibitors from the medicinal leech Hirudo medicinalis.

The medicinal leech Hirudo medicinalis produces various types of proteinase inhibitors: bdellins (inhibitors of trypsin, plasmin, and acrosin), hirustasin (inhibitor of tissue kallikrein, trypsin, alpha-chymotrypsin, and granulocyte cathepsin G), tryptase inhibitor, eglins (inhibitors of alpha-chymotrypsin, subtilisin, and chymasin and the granulocyte proteinases elastase and cathepsin G), inhibitor of factor Xa, hirudin (thrombin inhibitor), inhibitor of carboxypeptidase, and inhibitor of complement component C1s. This review summarizes data on their primary and tertiary structures, action mechanisms, and biological activities.

Neutral inhibitors of the serine protease factor Xa.

A neutral inhibitor of the serine protease factor Xa was identified via a high-throughput screen of a commercial library. The initial lead 1 demonstrated reversible and competitive inhibition kinetics for factor Xa and possessed a high degree of selectivity versus other related serine proteases. Initial modeling efforts and the generation of a series of analogues of 1 are described.

Development of oral heparin therapy for prophylaxis and treatment of deep venous thrombosis.

OBJECTIVE: To review the current research and published literature regarding the development of oral heparin therapy for the prophylaxis and treatment of deep venous thrombosis. BACKGROUND: Currently, the accepted practice of prophylaxis and/or treatment of acute deep venous thrombosis (DVT) is intravenous or subcutaneous (SQ) heparin followed by oral warfarin or SC low molecular weight heparin (LMWH) therapy followed by warfarin. Both of which are less than ideal. More recently, advances have been made towards an effective oral heparin preparation that would resolve many of the drawbacks to the current therapies. METHODS: A review of the current and relevant English literature identified via a search of the Medline database from January 1990 to present. RESULTS: Initial oral heparin therapy for DVT was unsuccessful due to presumed inadequate intestinal absorption as a result of heparin's molecular and structural characteristics. The development of oral heparin therapy, based on combining heparin with the carrier molecule Sodium N-(8[2-hydroxybenzoyl]amino) caprylate (SNAC) to enhance its intestinal absorption and bioavailability for the prophylaxis and treatment of DVT has been demonstrated to be effective in animal models. More recent efforts have been aimed at human trials. CONCLUSION: Recent advances in prophylaxis and treatment of DVT have stimulated great interest among researchers to develop an effective, convenient, and well tolerated oral therapy. An effective oral heparin therapy may represent an ideal method of prophylaxis and treatment of DVT.

The effects of triiodothyronine augmentation on antithrombin III levels in sepsis.

Sepsis and multisystem organ failure are often associated with disseminated intravascular coagulation and consumption of coagulation inhibitors such as antithrombin III (ATIII). The "sick euthyroid syndrome" is also seen in association with significant illnesses and consists of decreased levels of circulating triiodothyronine (T3). We evaluated whether T3 supplementation would affect ATIII levels in septic rats. Thirty Sprague-Dawley rats were divided into three groups: sham laparotomy (S) plus saline, cecal ligation and puncture (CLP) plus saline, and CLP plus T3 (3 ng/hour) via an osmotic minipump. Twenty-four hours after laparotomy blood was drawn, and T3 and ATIII levels were then compared with baseline values. T3 supplementation partially negated the sepsis-induced decrease in circulating T3 levels. The levels are expressed as percentage change from the levels before surgery (S, -12.9 +/- 3.1; CLP, -60.0 +/- 5.3; CLP + T3, -34.9 +/- 4.3; mean +/- standard error; P < 0.05). T3 supplementation also statistically changed the percentage difference in ATIII levels toward the control (S, 9.6 +/- 2.8; CLP, -37.9 +/- 5.4; CLP + T3, -16.0 +/- 4.5; mean +/- standard error; P < 0.01). T3 supplementation reduced the sepsis-induced decrease in ATIII levels. Whether this was accomplished by decreased consumption or increased production of ATIII via the direct anabolic effect of T3 on acute-phase protein synthesis in the liver is unknown and warrants further investigation.