PAR2 Activation on Human Kidney Tubular Epithelial Cells Induces Tissue Factor Synthesis, That Enhances Blood Clotting.

Coagulation abnormalities and increased risk of atherothrombosis are common in patients with chronic kidney diseases (CKD). Mechanisms that alter renal hemostasis and lead to thrombotic events are not fully understood. Here we show that activation of protease activated receptor-2 (PAR2) on human kidney tubular epithelial cells (HTECs), induces tissue factor (TF) synthesis and secretion that enhances blood clotting. PAR-activating coagulation-associated protease (thrombin), as well as specific PAR2 activators (matriptase, trypsin, or synthetic agonist 2f-LIGRLO-NH2 (2F), induced TF synthesis and secretion that were potently inhibited by PAR2 antagonist, I-191. Thrombin-induced TF was also inhibited by a PAR1 antagonist, Vorapaxar. Peptide activators of PAR1, PAR3, and PAR4 failed to induce TF synthesis. Differential centrifugation of the 2F-conditoned medium sedimented the secreted TF, together with the exosome marker ALG-2 interacting protein X (ALIX), indicating that secreted TF was associated with extracellular vesicles. 2F-treated HTEC conditioned medium significantly enhanced blood clotting, which was prevented by pre-incubating this medium with an antibody for TF. In summary, activation of PAR2 on HTEC stimulates synthesis and secretion of TF that induces blood clotting, and this is attenuated by PAR2 antagonism. Thrombin-induced TF synthesis is at least partly mediated by PAR1 transactivation of PAR2. These findings reveal how underlying hemostatic imbalances might increase thrombosis risk and subsequent chronic fibrin deposition in the kidneys of patients with CKD and suggest PAR2 antagonism as a potential therapeutic strategy for intervening in CKD progression.

Progress curve analysis of microtitre plate plasma clotting assays. Assessment of tissue factor levels.

MTP plasma clotting assays monitor the time course of fibrin formation in re-calcified plasma by absorbance measurements and are increasingly used as alternatives to traditional one-point clot time assays employed in clinical laboratories to detect thrombotic disorders. The parameters derived from these analyses are analogous to thromboelastography viz. time, rate and maximum extent of clot formation. The derived parameters, based on the whole course of the clotting reaction are more robust, informative and quantitative than single-point clot time assays. However, the parameters themselves are usually obtained arbitrarily by crude graphical analysis of subjectively selected points of progress curves. The current work aimed to investigate the sensitivity and reproducibility of an MTP clotting assay and examine its suitability for measuring tissue factor (TF) levels in cell culture medium and patient urine. The results demonstrate that progress curves can be analysed by fitting a logistic equation, derived from a simplified autocatalytic clot formation model. The parameters, maximum amplitude (Fm), rate constant (k), time to half-maximum amplitude (tm) and maximum rate of clot formation (vm), fit a power curve showing limiting effects with increasing TF concentration. Log/log plots of tm and k against TF concentration provide standard curves for assessment of unknowns.

Oral administration of dermatan sulphate reduces venous thrombus formation in vivo: potential use as a formulation for venous thromboembolism.

Dermatan sulphate (DS) is a sulphated polysaccharide that displays complexity in constituent sulphated disaccharides and interacts with proteins and signalling molecules to modulate numerous biological processes, including inhibition of the coagulation cascade and regulation of blood clotting and fibrinolysis. This study shows the antithrombotic and anticoagulant effects of DS prepared from bovine collagen waste liquor following oral and intravenous administrations in a deep vein thrombosis (DVT) rabbit model. In vitro, the prothrombin time, activated partial thromboplastin time, and thrombin citrated plasma clotting assays revealed that bovine DS had strong antithrombotic and anticoagulant effects comparable to low-molecular-weight heparin [Clexane® (enoxaparin sodium)]. In a DVT rabbit model, animals received intravenous and oral administrations of bovine DS and Clexane® providing further evidence that both agents had strong antithrombotic and anticoagulant effects by significantly reducing or preventing clot formation. Thromboelastography (TEG) assays revealed further that both bovine DS and Clexane® substantially prolonged the clotting time of recalcified citrated whole blood, but only bovine DS could retain clot strength suggesting that bovine DS had less effect on platelet-fibrin interactions. In conclusion, this is the first report that oral administration of DS from bovine collagen waste liquor reduces experimental venous thrombus formation warranting further research into bovine DS as an oral antithrombotic therapeutic.

Progress Curve Analysis of the one stage chromogenic assay for ecarin.

Snake venom prothrombin activators such as Ecarin are readily assayed by continuous spectrophotometric monitoring of p-nitroaniline production in a one step assay containing prothrombin and a p-nitroanilide peptide substrate for thrombin. The coupled reactions result in accelerating p-nitroaniline (pNA) production over the course of the assay giving non-linear progress curves, from which initial velocities are not readily obtained. Most studies therefore resort to approximate estimates of activity, based on the absorbance reached at an arbitrary time. A simple kinetic analysis of the coupled reactions shows that the early points of such curves should be fitted by second order polynomials, representing the accelerating reaction rate in µmol pNA/min/min. The first derivative of the polynomial then gives the increasing velocity of pNA production in µmol pNA/min over the time course of the assay. We demonstrate here that, with the substrate S2238, these rates can be converted to absolute thrombin concentrations using the Michaelis-Menten equation, substituted with values for kcat and Km. These thrombin concentrations increase linearly over the time course of the assay allowing the activity to be expressed in units, defined as µmol product/min, most commonly used to report enzyme activity.

Rapid serum tube technology overcomes problems associated with use of anticoagulants.

INTRODUCTION: Failure to obtain complete blood clotting in serum is a common laboratory problem. Our aim was to determine whether snake proth-rombin activators are effective in clotting blood and producing quality serum for analyte measurement in anticoagulated patients. MATERIALS AND METHODS: Whole blood clotting was studied in a total of 64 blood samples (41 controls, 20 Warfarin patients, 3 anticoagulated patients using snake venom prothrombin activator (OsPA)) with plain tubes. Coagulation was analysed using a visual assay, Hyland-Clotek and thromboelastography. Healthy control blood was spiked with a range of anticoagulants to determine the effectiveness of OsPa-induced clotting. A paired analysis of a Dabigatran patient and a control investigated the effectiveness of the OsPA clotting tubes. Biochemical analytes (N = 31) were determined for 7 samples on chemistry and immunoassay analysers and compared with commercial tubes. RESULTS: Snake venom prothrombin activators efficiently coagulated blood and plasma spiked with heparin and commonly used anticoagulants. Clotting was observed in the presence of anticoagulants whereas no clotting was observed in BDRST tubes containing 3 U/mL of heparin. Snake venom prothrombin activator enhanced heparinised blood clotting by shortening substantially the clotting time and improving significantly the strength of the clot. Comparison of 31 analytes from the blood of five healthy and two anticoagulated participants gave very good agreement between the analyte concentrations determined. CONCLUSIONS: Our results showed that the snake venom prothrombin activators OsPA and PtPA efficiently coagulated recalcified and fresh bloods with or without added anticoagulants. These procoagulants produced high quality serum for accurate analyte measurement.

Next-generation rapid serum tube technology using prothrombin activator coagulant: fast, high-quality serum from normal samples.

Background Incomplete blood clotting or latent clotting in serum is a common laboratory problem, especially for patients on anticoagulant therapy or when serum tubes are centrifuged before clotting is completed. We describe a novel approach to producing high-quality serum using snake venom prothrombin activator complex (OsPA) as an additive in blood collection tubes for non-anticoagulated (normal) individuals. Methods Plasma clotting assays were performed using a Hyland-Clotek instrument. Blood clotting was visually observed, and thromboelastography was also performed to determine the important parameters of coagulation. Thrombin generation was assayed using the chromogenic substrate S-2238, and biochemical analytes in the serum were determined on chemistry and immunoassay analysers. Fibrinogen was determined by either ELISA or Clauss fibrinogen assay. Results We initially showed that OsPA had strong coagulation activity in clotting not only recalcified citrated plasma and recalcified citrated whole blood, but also fresh whole blood in a clinical setting. The use of TEG clearly showed improved speed of clotting and generation of a firmer clot. We also showed that the use of OsPA to produce serum did not interfere with the determination of commonly measured biochemical analytes. The underlying clotting mechanism involves a burst of thrombin production at the initial stages of the clotting process upon contact with prothrombin in blood. Conclusions These results demonstrate rapid generation of high-quality serum, contributing to faster turnaround times with standardised quality samples, for accurate analyte determinations in normal individuals.

Anti-Coagulant and Anti-Thrombotic Properties of Blacklip Abalone (Haliotis rubra): In Vitro and Animal Studies.

Sulphated polysaccharides with anti-thrombotic and anti-coagulant activities have been found in various marine biota. In this study, a previously characterised anti-thrombotic and anti-coagulant extract from blacklip abalone was fractionated by anion exchange chromatography (AEC), pooled (on a sulphated polysaccharide basis) and administered to Wistar rats via oral gavage (N = 8) for assessment as an oral therapeutic. To ensure that the preparation had anti-coagulant activity prior to oral administration, it was assessed in rat blood by thromboelastography (TEG) significantly increasing reaction (R) time (or time until clot formation). Following in vitro confirmation of anti-coagulant activity, 40 mg of the preparation was orally administered to rats with blood samples collected at 2, 4, and 6 h post-gavage. Assessment of all blood samples by TEG showed some prolongation of R time from 355 to 380 s after 4 h. Dosing of the post-gavage blood samples with the abalone preparation to confirm anti-thrombotic activity in vitro revealed residual anti-coagulant activity, further suggesting that oral administration did increase anti-coagulant potential in the collected blood but that bioavailability was low. Assessment of tissues and haematological parameters showed no obvious harmful effects of the abalone preparation in animals. In summary, even though oral administration of fractionated and pooled blacklip abalone extract to rats delayed clotting after 4 h, bioavailability of the preparation appeared to be low and may be more appropriate for intravenous administration as an anti-thrombotic or anti-coagulant therapeutic.

In vitro anti-thrombotic and anti-coagulant properties of blacklip abalone (Haliotis rubra) viscera hydrolysate.

Abalone viscera contain sulphated polysaccharides with anti-thrombotic and anti-coagulant activities. In this study, a hydrolysate was prepared from blacklip abalone (Haliotis rubra) viscera using papain and bromelain and fractionated using ion exchange and size exclusion chromatography. Hydrolysates and fractions were investigated for in vitro thrombin inhibition mediated through heparin cofactor II (HCII) as well as anti-coagulant activity in plasma and whole blood. On the basis of sulphated polysaccharide concentration, the hydrolysate inhibited thrombin through HCII with an inhibitor concentration at 50% (IC50) of 16.5 µg/mL compared with 2.1 µg/mL for standard heparin. Fractionation concentrated HCII-mediated thrombin inhibition down to an IC50 of 1.8 µg/mL and improved anti-coagulant activities by significantly delaying clotting time. This study confirmed the presence of anti-thrombotic and anti-coagulant molecules in blacklip abalone viscera and demonstrated that these activities can be enriched with a simple chromatography regime. Blacklip abalone viscera warrant further investigation as a source of nutraceutical or functional food ingredients. Graphical abstract Schematic showing preparation of bioactive extracts and fractions from blacklip abalone.

Evaluation of the Greiner Bio-One serum separator BCA Fast Clot tube.

BACKGROUND: Current commercial tubes have difficulties in producing "true" serum from all blood samples even within the recommended clotting times. Hence, Becton Dickinson (BD) and now Greiner have produced tubes containing thrombin as the procoagulant to reduce the clotting time and increase the possibility of producing serum from anticoagulated blood samples. METHODS: The Greiner BCA Fast Clot (GBBCAFC) tube was evaluated in a hospital environment using 40 participants, (30 healthy and 10 undergoing renal dialysis) for 32 analytes against the Greiner lithium heparin tube and the BD Rapid Serum Tubes (BD RST) tube measured on Beckman DxC 800 and DxI 800 analyzers. Clotting strength was also examined using thromboelastography (TEG). RESULTS: The analytes results showed there was a very close agreement between the BD RST tube and GBBCAFC tube in comparison with lithium heparin plasma. The result comparison data showed equivalent performance with lower levels of hemolysis. The prolonged storage study also showed very similar agreement between the BD RST and the GBBCAFC tubes. Likewise, the TEG data showed there was very little difference in clotting ability between the tubes, and neither was capable of producing true serum from blood spiked with 2 U heparin/mL of blood. CONCLUSIONS: The study showed the GBBCAFC tube with the combination of the two procoagulants blood clotting activator and thrombin produced comparable performance with the lithium heparin plasma and the BD RST serum samples.

Rapid Radiations and the Race to Redundancy: An Investigation of the Evolution of Australian Elapid Snake Venoms.

Australia is the stronghold of the front-fanged venomous snake family Elapidae. The Australasian elapid snake radiation, which includes approximately 100 terrestrial species in Australia, as well as Melanesian species and all the world's sea snakes, is less than 12 million years old. The incredible phenotypic and ecological diversity of the clade is matched by considerable diversity in venom composition. The clade's evolutionary youth and dynamic evolution should make it of particular interest to toxinologists, however, the majority of species, which are small, typically inoffensive, and seldom encountered by non-herpetologists, have been almost completely neglected by researchers. The present study investigates the venom composition of 28 species proteomically, revealing several interesting trends in venom composition, and reports, for the first time in elapid snakes, the existence of an ontogenetic shift in the venom composition and activity of brown snakes (Pseudonaja sp.). Trends in venom composition are compared to the snakes' feeding ecology and the paper concludes with an extended discussion of the selection pressures shaping the evolution of snake venom.

Alteration of blood clot structures by interleukin-1 beta in association with bone defects healing.

The quality of hematomas are crucial for successful early bone defect healing, as the structure of fibrin clots can significantly influence the infiltration of cells, necessary for bone regeneration, from adjacent tissues into the fibrin network. This study investigated if there were structural differences between hematomas from normal and delayed healing bone defects and whether such differences were linked to changes in the expression of IL-1ß. Using a bone defect model in rats, we found that the hematomas in the delayed healing model had thinner fibers and denser clot structures. Moreover, IL-1ß protein levels were significantly higher in the delayed healing hematomas. The effects of IL-1ß on the structural properties of human whole blood clots were evaluated by thrombelastograph (TEG), scanning electronic microscopy (SEM), compressive study, and thrombolytic assays. S-nitrosoglutathione (GSNO) was applied to modulate de novo hematoma structure and the impact on bone healing was evaluated in the delayed healing model. We found that GSNO produced more porous hematomas with thicker fibers and resulted in significantly enhanced bone healing. This study demonstrated that IL-1ß and GSNO had opposing effects on clot architecture, the structure of which plays a pivotal role in early bone healing.

Influence of Interleukin-1 Beta on Platelet-Poor Plasma Clot Formation: A Potential Impact on Early Bone Healing.

OBJECTIVES: Hematoma quality (especially the fibrin matrix) plays an important role in the bone healing process. Here, we investigated the effect of interleukin-1 beta (IL-1ß) on fibrin clot formation from platelet-poor plasma (PPP). METHODS: Five-milliliter of rat whole-blood samples were collected from the hepatic portal vein. All blood samples were firstly standardized via a thrombelastograph (TEG), blood cell count, and the measurement of fibrinogen concentration. PPP was prepared by collecting the top two-fifths of the plasma after centrifugation under 400 × g for 10 min at 20°C. The effects of IL-1ß cytokines on artificial fibrin clot formation from PPP solutions were determined by scanning electronic microscopy (SEM), confocal microscopy (CM), turbidity, and clot lysis assays. RESULTS: The lag time for protofibril formation was markedly shortened in the IL-1ß treatment groups (243.8 ± 76.85 in the 50 pg/mL of IL-1ß and 97.5 ± 19.36 in the 500 pg/mL of IL-1ß) compared to the control group without IL-1ß (543.8 ± 205.8). Maximal turbidity was observed in the control group. IL-1ß (500 pg/mL) treatment significantly decreased fiber diameters resulting in smaller pore sizes and increased density of the fibrin clot structure formed from PPP (P < 0.05). The clot lysis assay revealed that 500 pg/mL IL-1ß induced a lower susceptibility to dissolution due to the formation of thinner and denser fibers. CONCLUSION: IL-1ß can significantly influence PPP fibrin clot structure, which may affect the early bone healing process.

Characterization and structural analysis of a potent anticoagulant phospholipase A2 from Pseudechis australis snake venom.

Pseudechis australis is one of the most venomous and lethal snakes in Australia. Numerous phospholipase A2 (PLA2) isoforms constitute a major portion of its venom, some of which have previously been shown to exhibit not only enzymatic, but also haemolytic, neurotoxic and anticoagulant activities. Here, we have purified a potent anticoagulant PLA2 (identified as PA11) from P. australis venom to investigate its phospholipase, anticoagulant, haemolytic and cytotoxic activities and shown that addition of 11 nM PA11 resulted in a doubling of the clotting time of recalcified whole blood. We have also demonstrated that PA11 has high PLA2 enzymatic activity (10.9 × 10(4) Units/mg), but low haemolytic activity (0.6% of red blood cells hydrolysed in the presence of 1 nM PA11). PA11 at a concentration lower than 600 nM is not cytotoxic towards human cultured cells. Chemical modification experiments using p-bromophenacyl bromide have provided evidence that the catalytic histidine of PA11 is critical for the anticoagulant activity of this PLA2. PA11 that was subjected to trypsin digestion without previous reduction and alkylation of the disulfide bonds maintained enzymatic and anticoagulant activity, suggesting that proteolysis alone cannot abolish these properties. Consistent with these results, administration of PA11 by gavage in a rabbit stasis thrombosis model increased the clotting time of recalcified citrated whole blood by a factor of four. These data suggest that PA11 has potential to be developed as an anticoagulant in a clinical setting.

TGFß isoforms and receptors mRNA expression in breast tumours: prognostic value and clinical implications.

BACKGROUND: Transforming growth factor beta (TGFß) signalling is involved in both tumour suppression and tumour progression. The mRNA expression levels of the TGFß isoforms and receptors in breast tumours may have prognostic value and clinical implications. METHODS: The mRNA levels of TGFB1, TGFB2, TGFB3, TGFBR1 and TGFBR2 were analysed in primary breast tumours and adjacent normal breast tissues, and the associations with tumour characteristics and patients' overall and relapse-free survival were evaluated, using the public gene expression microarray data from The Cancer Genome Atlas (n = 520) and the Gene Expression Omnibus (four datasets) and our quantitative real-time PCR validation data (n = 71). RESULTS: Significantly higher TGFB1 and TGFB3 mRNA levels and lower TGFBR2 mRNA levels were observed in primary tumours compared with their paired normal tissues. TGFB1 mRNA expression was seemly lower in triple-negative tumours and in tumours from lymph node-negative patients. TGFB3 mRNA expression was significantly lower in estrogen receptor-negative/progesterone receptor-negative/Basal-like/Grade 3 tumours. High TGFB2, TGFB3 and TGFBR2 mRNA levels in tumours were generally associated with better prognosis for patients, especially those diagnosed with lymph node-negative diseases. High TGFBR1 mRNA levels in tumours were associated with poorer clinical outcomes for patients diagnosed with small (diameter ≤ 2 cm) tumours. CONCLUSIONS: The results indicate a reduced responsiveness of tumour cells to TGFß, a preferential up-regulation of TGFB1 in malignant tumours and a preferential up-regulation of TGFB3 in premalignant tumours. The results may not only provide prognostic value for patients but also assist in classifying tumours according to their potential responses to TGFß and selecting patients for TGFß signalling pathway targeted therapies.

ß-Adducin siRNA disruption of the spectrin-based cytoskeleton in differentiating keratinocytes prevented by calcium acting through calmodulin/epidermal growth factor receptor/cadherin pathway.

Here, we report that siRNA transfection of ß-adducin significantly disrupted the spectrin-based cytoskeleton and cytoskeletal arrangements of both ß-adducin and PKCδ by substantially inhibiting the expression of ß-adducin, spectrin and PKCδ proteins in differentiating keratinocytes. However, extracellular Ca2+ treatment blocked the inhibitory effects of the ß-adducin siRNA. Ca2+ also prevented the significant down-regulation of two differentiation markers involucrin and K1/10 and the distinct up-regulation of proliferation marker K14 in ß-adducin siRNA transfected keratinocytes. In addition, ß-adducin knockdown resulted in a substantial reduction of epidermal growth factor receptor (EGFR), cadherin and ß-catenin and enhanced phosphorylation of EGFR on tyrosine 1173 and Ca2+ prevented these changes. Furthermore, Ca2+ blocked the inhibitory effects of ß-adducin siRNA on the expression of calmodulin, phosphorylated-calmodulin (P-CaM((Tyr138))) and myristoylated alanine-rich C-kinase substrate (MARCKS) in keratinocytes. Co-immunoprecipitation studies further revealed that calmodulin, not MARCKS, strongly interacted with EGFR, cadherin and ß-catenin. Our data suggest that Ca2+ plays an important role in regulating the expression and function of ß-adducin to sustain normal organization of the spectrin-based cytoskeleton and the differentiation properties in keratinocytes through the calmodulin/EGFR/cadherin signaling pathway.

Four major factors regulate phosphatidylinositol 3-kinase signaling pathway in cancers induced by infection of human papillomaviruses.

Epidemiological surveys and molecular studies have indicated that infection of human papillomavirus (HPV)itself is necessary but insufficient for completing transformation of the human epithelial cells in vivo to lead to different cancers. Mounting evidence exists that HPV E6/E7 oncoproteins indeed alter the cellular and molecular events in their transformed cells to induce cancers through a phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway. The PI3K/AKT/mTOR signaling pathway is, nonetheless, of the central importance, which tightly modulates many cellular events that occur in cells to lead them to be cancerous under the action of oncogenic factors. The cancinogenic roles of the PI3K/AKT/mTOR signaling in HPV-induced cancers are generally regulated by different upstream signaling molecules such as upstream receptor tyrosine kinases. In this article, we review that the four major upstream signaling molecules (growth factor receptor, notch receptor, Ras and PI3KCA genes) regulate PI3K/AKT/mTOR pathway to confer oncogenicity in HPV-immortalized epithelial cells and various transformed phenotypes.

Calcium prevents retinoic acid-induced disruption of the spectrin-based cytoskeleton in keratinocytes through the Src/PI3K-p85α/AKT/PKCδ/ß-adducin pathways.

We have previously reported that spectrin increases dramatically in amount and is assembled into the cytoskeleton in differentiating keratinocytes both in vitro and in vivo (Zhao et al., PLoS ONE 6 (12) (2011) e28267). We demonstrate here that extracellular calcium (Ca2+) enhances differentiation of keratinocytes and that this is associated with increased spectrin expression and formation of a spectrin-based cytoskeleton. While Retinoic acid (RA) also enhanced keratinocyte differentiation, it abrogated the spectrin-based cytoskeleton in keratinocytes. Furthermore, RA substantially inhibited expression of both Src and PI3K-p85α and consequently the amounts of specific phosphorylation of both of these proteins. RA also enhanced AKT expression and dramatically induced phosphorylation of AKT((Thr308)), accompanied by phosphorylation of both PKCδ((Thr505)) and ß-adducin((Ser662)) and upregulated cyclin D2 and down-regulated cyclin B1. On the other hand, Ca2+ overcame the inhibitory effects of RA on expression of Src, PI3K-p85α and cyclin B1 by maintaining high levels of phosphorylation of both Src((Tyr527)) and PI3K-p85α and preventing phosphorylation of AKT((Thr308)), PKCδ((Thr505)) and ß-adducin((Ser662)). These data highlight the importance of Ca2+ in both spectrin expression and the organizational integrity of the spectrin-based cytoskeleton in differentiating keratinocytes and assist in elucidating the signalling pathways involved.

Nutraceuticals and chemotherapy induced peripheral neuropathy (CIPN): a systematic review.

Chemotherapy induced peripheral neuropathy [CIPN] is a common significant and debilitating side effect resulting from the administration of neurotoxic chemotherapeutic agents. These pharmaco-chemotherapeutics can include taxanes, vinca alkaloids and others. Moderate to severe CIPN significantly decreases the quality of life and physical abilities of cancer patients and current pharmacotherapy for CIPN e.g. Amifostine and antidepressants have had limited efficacy and may themselves induce adverse side effects. To determine the potential use of nutraceuticals i.e. vitamin E, acetyl-L-carnitine, glutamine, glutathione, vitamin B6, omega-3 fatty acids, magnesium, calcium, alpha lipoic acid and n-acetyl cysteine as adjuvants in cancer treatments a systematic literature review was conducted. Revised clinical studies comprised of randomized clinical trials that investigated the anti-CIPN effect of nutraceuticals as the adjuvant intervention in patients administered chemotherapy. Twenty-four studies were assessed on methodological quality and limitations identified. Studies were mixed in their recommendations for nutraceuticals. Currently no agent has shown solid beneficial evidence to be recommended for the treatment or prophylaxis of CIPN. The standard of care for CIPN includes dose reduction and/or discontinuation of chemotherapy treatment. The management of CIPN remains an important challenge and future studies are warranted before recommendations for the use of supplements can be made.

The structure of human microplasmin in complex with textilinin-1, an aprotinin-like inhibitor from the Australian brown snake.

Textilinin-1 is a Kunitz-type serine protease inhibitor from Australian brown snake venom. Its ability to potently and specifically inhibit human plasmin (K(i) = 0.44 nM) makes it a potential therapeutic drug as a systemic anti-bleeding agent. The crystal structures of the human microplasmin-textilinin-1 and the trypsin-textilinin-1 complexes have been determined to 2.78 Å and 1.64 Å resolution respectively, and show that textilinin-1 binds to trypsin in a canonical mode but to microplasmin in an atypical mode with the catalytic histidine of microplasmin rotated out of the active site. The space vacated by the histidine side-chain in this complex is partially occupied by a water molecule. In the structure of microplasminogen the χ(1) dihedral angle of the side-chain of the catalytic histidine is rotated by 67° from its "active" position in the catalytic triad, as exemplified by its location when microplasmin is bound to streptokinase. However, when textilinin-1 binds to microplasmin the χ(1) dihedral angle of this amino acid residue changes by -157° (i.e. in the opposite rotation direction compared to microplasminogen). The unusual mode of interaction between textilinin-1 and plasmin explains textilinin-1's selectivity for human plasmin over plasma kallikrein. This difference can be exploited in future drug design efforts.

Identification and characterisation of Kunitz-type plasma kallikrein inhibitors unique to Oxyuranus sp. snake venoms.

As part of a wider study on Australian snake venom components, we have identified and characterised Kunitz-type protease inhibitors from the venoms of Oxyuranus scutellatus and Oxyuranus microlepidotus (Australian taipans) with plasma kallikrein inhibitory activity. Each inhibitor had a mass of 7 kDa and was purified from the venom as part of a protein complex. Mass spectrometry and N-terminal sequencing was employed to obtain amino acid sequence information for each inhibitor and a recombinant form of the O. scutellatus inhibitor, termed TSPI, was subsequently expressed and purified. TSPI was investigated for inhibition against a panel of 12 enzymes involved in haemostasis and estimates of the K(i) value determined for each enzyme. TSPI was found to be a broad spectrum inhibitor with most potent inhibitory activity observed against plasma kallikrein that corresponded to a K(i) of 0.057 ± 0.019 nM. TSPI also inhibited fibrinolysis in whole blood and prolonged the intrinsic clotting time. These inhibitors are also unique in that they appear to be found only in Oxyuranus sp. venoms.