Toxico-Kinetics of Recombinant VWF In Non-Human Primates and Rabbits

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1414-1414
Author(s):  
Eva-Maria Muchitsch ◽  
Barbara Dietrich ◽  
Hanspeter Rottensteiner ◽  
Herbert Gritsch ◽  
Hartmut J. Ehrlich ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Dependent Manner ◽  
Cynomolgus Monkeys ◽  
Toxicological Effect ◽  
Safety Margins ◽  
Hemostatic Activity ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Kinetics Of

Abstract Abstract 1414 Von Willebrand factor (VWF) is cleaved by the plasma metalloprotease ADAMTS13 that regulates the hemostatic activity of VWF by limiting its multimeric size in the human system. We showed previously by in vitro and ex vivo studies that human recombinant VWF (rVWF) is virtually resistant to the proteolytic activity of murine and rat ADAMTS13, whereas ADAMTS13 from rabbits and cynomolgus monkeys is able to cleave human rVWF. Here we tested the pharmacological behavior of human rVWF in rabbits and cynomolgus monkeys. The animals were infused once with different doses of human rVWF. VWF antigen rose sharply in a dose-dependent manner (∼25 IU/ml VWF:Ag for the highest dose, 15 min after injection) and then declined gradually (∼7 IU/ml VWF:Ag for the highest dose, 18 hours after injection). By contrast, the ADAMTS13 activity did not show relevant changes throughout the entire test period in the rabbit or in the monkey samples, indicating that an excess of intravenously administered rVWF as the substrate does not exhaust its enzyme ADAMTS13. Most importantly, neither rabbits nor cynomolgus monkeys showed any exaggerated pharmacological or toxic effects upon rVWF administration. Even the administration of 14 daily doses of rVWF to cynomolgus monkeys did not lead to any toxicological effect. Our data indicate that rabbits and cynomolgus monkeys, two species with a sufficient rVWF cleavage capacity by endogenous ADAMTS13, are appropriate animal models for a meaningful preclinical evaluation of the rVWF product, which allows the therapeutic safety margins for human patients to be determined. Disclosures: Muchitsch: Baxter Innovations GmbH: Employment. Dietrich:Baxter Innovations GmbH: Employment. Rottensteiner:Baxter Innovations GmbH: Employment. Gritsch:Baxter Innovations GmbH: Employment. Ehrlich:Baxter Innovations GmbH: Employment. Turecek:Baxter Innovations GmbH: Employment. Schwarz:Baxter Innovations GmbH: Employment.

Cleavage of Recombinant and Plasma-Derived VWF by Human ADAMTS13

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1415-1415
Author(s):  
Hanspeter Rottensteiner ◽  
Katalin Varadi ◽  
Susanne Vejda ◽  
Hartmut J. Ehrlich ◽  
Friedrich Scheiflinger ◽  
...  
Keyword(s):  
Shear Stress ◽  
Human Plasma ◽  
Phase 1 ◽  
Dependent Manner ◽  
Normal Human ◽  
Typical Satellite ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Kinetics Of

Abstract Abstract 1415 A recombinant human CHO-expressed von Willebrand factor (rVWF) consisting of ultra-high molecular weight (UHMW) multimers resembles the VWF stored in Weibel-Palade bodies of endothelial cells. Once secreted into plasma, UHMW multimers are rapidly cleaved by ADAMTS13 and are usually missing in plasma-derived VWF (pdVWF). Here we analyzed in vitro whether the kinetics of cleavage of rVWF by ADAMTS13 is similar to that of pdVWF. The kinetics of ADAMTS13-mediated proteolysis of rVWF were explored under denaturing conditions (1.5 M urea) or under shear stress so as to expose the ADAMTS13 cleavage site of VWF. Multiple assays showed that rVWF was efficiently cleaved by ADAMTS13. UHMW multimers disappeared within seconds at physiological concentrations of ADAMTS13. Using lower concentrations of ADAMTS13 (10-30 mU/ml, equivalent to 1–3% of normal human plasma), UHMW were cleaved within 30 minutes. The typical satellite bands appeared very early in an ADAMTS13 dose-dependent manner. Virtually the same results were obtained when human plasma was used as a source for ADAMTS13. Although pdVWF differs from rVWF in its multimeric structure, the decrease in activity was similar for rVWF and pdVWF. Finally, the extent of ADAMTS13 cleavage was similar for rVWF and pdVWF when exposed to shear stress using a cone-plate viscometer. Our data clearly indicate that rVWF is a good substrate for ADAMTS13. Ongoing phase 1 studies demonstrated that rVWF is indeed processed by the protease when administered in humans with severe VWD. Disclosures: Rottensteiner: Baxter Innovations GmbH: Employment. Varadi:Baxter Innovations GmbH: Employment. Vejda:Baxter Innovations GmbH: Employment. Ehrlich:Baxter Innovations GmbH: Employment. Scheiflinger:Baxter Innovations GmbH: Employment. Schwarz:Baxter Innovations GmbH: Employment. Turecek:Baxter Innovations GmbH: Employment.

Significance of Platelet β-Adrenoceptors for Platelet Responses In Vivo and In Vitro

1992 ◽  
Vol 68 (06) ◽  
pp. 687-693 ◽  
Author(s):  
P T Larsson ◽  
N H Wallén ◽  
A Martinsson ◽  
N Egberg ◽  
P Hjemdahl
Keyword(s):  
Ex Vivo ◽  
High Dose ◽  
Platelet Aggregability ◽  
Adrenoceptor Agonist ◽  
Dose Infusion ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThe significance of platelet β-adrenoceptors for platelet responses to adrenergic stimuli in vivo and in vitro was studied in healthy volunteers. Low dose infusion of the β-adrenoceptor agonist isoprenaline decreased platelet aggregability in vivo as measured by ex vivo filtragometry. Infusion of adrenaline, a mixed α- and β-adrenoceptor agonist, increased platelet aggregability in vivo markedly, as measured by ex vivo filtragometry and plasma β-thromboglobulin levels. Adrenaline levels were 3–4 nM in venous plasma during infusion. Both adrenaline and high dose isoprenaline elevated plasma von Willebrand factor antigen levels β-Blockade by propranolol did not alter our measures of platelet aggregability at rest or during adrenaline infusions, but inhibited adrenaline-induced increases in vWf:ag. In a model using filtragometry to assess platelet aggregability in whole blood in vitro, propranolol enhanced the proaggregatory actions of 5 nM, but not of 10 nM adrenaline. The present data suggest that β-adrenoceptor stimulation can inhibit platelet function in vivo but that effects of adrenaline at high physiological concentrations are dominated by an α-adrenoceptor mediated proaggregatory action.

Von Willebrand’s Disease caused by Compound Heterozygosity for a Substitution Mutation (T1156M) in the D3 Domain of the Von Willebrand Factor and a Stop Mutation (Q2470X)

2002 ◽  
Vol 88 (09) ◽  
pp. 421-426 ◽  
Author(s):  
Stefan Lethagen ◽  
Christina Isaksson ◽  
Charlotta Schaedel ◽  
Lars Holmberg
Keyword(s):  
Von Willebrand Factor ◽  
Null Allele ◽  
Dependent Manner ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Stop Mutation ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryHereditary defects of the von Willebrand factor (VWF) gene cause von Willebrand’s disease (VWD) which shows great variability dependent on the nature and location of the mutation. We here describe the characteristics of a substitution of methionine for threonine 1156 in the D3 domain of the VWF, i.e. the domain involved in the intracellular multimerization of pro-VWF dimers. A VWD patient with severe symptoms was a compound heterozygote for the T1156M mutation and a null allele (Q2470X) on the other chromosome. This led to marked reduction of plasma VWF concentration to about 0.05 U/ml and an abnormality of VWF multimers as in type 2A VWD. Expression in vitro of the mutation demonstrated that 1156M-VWF is secreted from COS-7 cells in a much reduced amount and lacking large multimers. When coexpressed with normal VWF 1156M-VWF decreased the secretion of normal VWF in a dose-dependent manner, the secreted VWF showing all the multimers. Two relatives of the propositus were single heterozygotes for the T1156M mutation and were either asymptomatic or had the manifestations of mild type 1 VWD. The expression data and studies of platelet VWF indicate that the T1156M mutation results in intracellular retention of VWF rather than impaired synthesis. Three other members of the family were heterozygotes for the Q2470X mutation and demonstrated the variable expressivity of a null allele.

Endothelial von Willebrand factor recruits platelets to atherosclerosis-prone sites in response to hypercholesterolemia

Blood ◽  
2002 ◽  
Vol 99 (12) ◽  
pp. 4486-4493 ◽  
Author(s):  
Gregor Theilmeier ◽  
Carine Michiels ◽  
Erik Spaepen ◽  
Ingrid Vreys ◽  
Désiré Collen ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Human Platelets ◽  
Platelet Glycoprotein ◽  
Perfusion Studies ◽  
Von Willebrand ◽  
Willebrand Factor

Platelets are thought to play a causal role during atherogenesis. Platelet-endothelial interactions in vivo and their molecular mechanisms under shear are, however, incompletely characterized. Here, an in vivo platelet homing assay was used in hypercholesterolemic rabbits to track platelet adhesion to plaque predilection sites. The role of platelet versus aortic endothelial cell (EC) activation was studied in an ex vivo flow chamber. Pathways of human platelet immobilization were detailed during in vitro perfusion studies. In rabbits, a 0.125% cholesterol diet induced no lesions within 3 months, but fatty streaks were found after 12 months. ECs at segmental arteries of 3- month rabbits expressed more von Willebrand factor (VWF) and recruited 5-fold more platelets than controls (P < .05, n = 5 and 4, respectively). The 3-month ostia had an increased likelihood to recruit platelets compared to control ostia (56% versus 18%, P < .0001, n = 89 and 63, respectively). Ex vivo, the adhesion of 3-month platelets to 3-month aortas was 8.4-fold increased compared to control studies (P < .01, n = 7 and 5, respectively). In vitro, endothelial VWF–platelet glycoprotein (GP) Ib and platelet P-selectin– endothelial P-selectin glycoprotein ligand 1 interactions accounted in combination for 83% of translocation and 90% of adhesion (P < .01, n = 4) of activated human platelets to activated human ECs. Platelet tethering was mainly mediated by platelet GPIbα, whereas platelet GPIIb/IIIa contributed 20% to arrest (P < .05). In conclusion, hypercholesterolemia primes platelets for recruitment via VWF, GPIbα, and P-selectin to lesion-prone sites, before lesions are detectable.

Hemoglobin Blocks Von Willebrand Factor Proteolysis by ADAMTS-13: A Mechanism Associated with Acquired ADAMTS-13 Deficiency in Patients with Sickle Cell Disease

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3919-3919
Author(s):  
Zhou Zhou ◽  
Han Hyojeong ◽  
Miguel A. Cruz ◽  
Jose A. Lopez ◽  
Jing-fei Dong ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Von Willebrand Factor ◽  
Elevated Level ◽  
Dependent Manner ◽  
Cell Disease ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract One of the hallmark events of sickle cell disease (SCD) is vasoocclusion and episodic pain crisis. Although the mechanism of vascular occlusion is very complicated, processes like thrombosis and thromboembolism have been recognized to play an important role in the development of such clinical manifestation in SCD. Studies have shown that the von Willebrand factor (VWF), especially the ultra-large (UL) multimers play a major role in vasoocclusion, which clearly indicates a possible impairment of the VWF-cleaving metalloproteae ADAMTS-13 in these patients with SCD. In a recent work, indeed we have mentioned that the plasma ADAMTS-13 in patients with SCD having normal antigen level showed 35% less protease activity than the normal. There may be several plasma factors responsible for the acquired deficiency of ADAMTS-13 in SCD. Since, the increasing evidences suggest that the elevated level of extracellular hemoglobin (Hb) in plasma parallely associated with the pathogenesis of SCD, we investigated the effects of extracellular Hb on VWF proteolysis by ADAMTS-13. We observed that purified Hb dose-dependently inhibited the ADAMTS-13 cleavage of recombinant(r) VWF and endothelial ULVWF multimers under static and flow conditions. Hb bound to VWF multimers in a saturation-dependent manner and more potently to the rVWFA2 domain (affinity Kd~24nM), which contains the cleavage site for ADAMTS-13. Hb bound also to the ADAMTS-13 (Kd~65nM), with 2.7 times less affinity than to VWFA2. The bindings were neither calcium-dependent nor affected by haptoglobin. However, it is the Hb-binding to VWF that prevented the substrate from being cleaved by ADAMTS-13. These in vitro findings are consistent with the in vivo observations in patients with SCD. An elevated level of extracellular Hb in plasma was inversely correlated (linear regression, r2 =0.6354) with the low activity of ADAMTS-13 in a cohort of ten adult patients with SCD (mean±SE, Hb 346±138 mg/l; activity 33.3±30%) compared to age and gender-matched normal individuals (n=10; Hb 24±8 mg/l; activity 76.2±16%). The data together suggest that patients with SCD suffer from acquired ADAMTS-13 deficiency, primarily because Hb competitively binds and inhibits the proteolysis of VWF multimers, leading to ULVWF accumulation on vascular endothelium and in circulation. The Hb-VWF interaction may therefore be considered as a therapeutic target for reducing thrombotic and vasoocclusive complications in patients with severe hemolysis such as those with SCD.

scholarly journals Ex Vivo Evaluation of the Effect of Plasma-Derived Factor VIII/Von Willebrand Factor in Patients with Severe Hemophilia_A on Prophylaxis with Emicizumab By Thrombin Generation Assay

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4233-4233
Author(s):  
Maria-Isabel Bravo ◽  
Aida Raventós ◽  
Alba Pérez ◽  
Elena G Arias-Salgado ◽  
María Teresa Alvarez Román ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Research Funding ◽  
Thrombin Generation ◽  
Ex Vivo ◽  
Concomitant Treatment ◽  
Healthy Controls ◽  
Normal Range ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Introduction: Hemophilia A (HA) patients under emicizumab prophylaxis treatment may require the concomitant use of procoagulant factors for breakthrough bleedings or immune tolerance induction. Thromboembolic events have been described with the concomitant use of emicizumab and activated prothrombin complex concentrate (aPCC), but not with recombinant activated factor VII (rFVIIa). Previous studies showed that the in vitro combination of emicizumab and plasma-derived Factor VIII/Von Willebrand Factor (pdFVIII/VWF) had a non-additive effect on thrombin generation (TG)(Bravo M-I, et al J Thromb Haemost. 2020;18:1934-39). The aim of this study was to evaluate the TG resulting from ex vivo combination of plasma samples from HA patients treated with emicizumab, with a pdFVIII/VWF concentrate (Fanhdi ®, Grifols). Methods: Twelve adult patients with severe HA without inhibitors on prophylaxis with emicizumab and nine healthy controls were included in the study. Blood samples were drawn in citrate plus corn trypsin inhibitor tubes. Then, platelet poor plasma (PPP) was collected for the TG assay, which measures the whole kinetics of TG. Thrombin peak (TP) and endogenous thrombin potential (ETP) were calculated using calibrated automated thrombogram (Thrombinoscope ™ software, Stago) after in vitro activation of coagulation by trigger solution, PPP Reagent LOW TM (4 μM phospholipids/1 pM tissue factor), fluorogenic substrate and CaCl 2 (FLUKAkit TM) reagents (Diagnostica Stago). Fluorescence was read in a Fluoroskan Ascent reader (Thermo) equipped with a 390/460 filter set. Samples were spiked with increasing concentrations of pdFVIII/VWF (10 to 400 IU/dL), rFVIIa (0.9 µg/mL) or aPCC (0.5 U/mL). Results: TG from healthy control samples was measured to establish TP and ETP normal ranges. TP and ETP results obtained from HA plasma with emicizumab were lower than in healthy controls. The addition of pdFVIII/VWF as of 25 IU/kg (prophylaxis dose in HA w/o inhibitors) to samples from HA patients concomitantly treated with emicizumab restored TP and ETP levels within healthy controls normal range (Table 1). Increasing ex vivo concentrations of pdFVIII/VWF maintained TP and ETP similar to healthy controls. The highest concentration of concomitant treatment with pdFVIII/VWF (200 IU/kg) and emicizumab did not result in excessive TP and, importantly, ETP levels were always within the normal range. The combination with the bypassing agent rFVIIa moderately increased TP and ETP values up to normal range. However, when HA plasma was spiked with aPCC in the presence of emicizumab, TP and ETP dramatically increased above normal range resulting in a synergistic procoagulant profile. Conclusions: The concomitant use of pdFVIII/VWF in patients with prophylaxis with emicizumab did not trigger a multiplying effect on TG. These results were aligned with previous in vitro data and suggested the low risk of overdose and thrombotic events of concomitant treatment emicizumab with the pdFVIII/VWF concentrate in HA patients. Figure 1 Figure 1. Disclosures Bravo: Grifols: Current Employment, Other: Grifols is a manufacturer of the pdFVIII/VWF concentrate, Fanhdi®. Raventós: Grifols: Current Employment, Other: Grifols is a manufacturer of the pdFVIII/VWF concentrate, Fanhdi®. Pérez: Grifols: Current Employment, Other: Grifols is a manufacturer of the pdFVIII/VWF concentrate, Fanhdi®. Alvarez Román: Grifols: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Novo-Nordisk: Consultancy, Honoraria, Research Funding; Sobi: Consultancy, Honoraria, Research Funding; Octapharma: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; CSL-Behring: Consultancy, Honoraria, Research Funding; Biomarin: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding. Butta: CSL-Behring: Research Funding; Roche: Speakers Bureau; Takeda: Research Funding, Speakers Bureau; Novo-Nordisk: Speakers Bureau. Jiménez-Yuste: Bayer: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; CSL Behring: Consultancy, Honoraria, Research Funding; BioMarin: Consultancy; Sobi: Consultancy, Honoraria, Research Funding; Octapharma: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; NovoNordisk: Consultancy, Honoraria, Research Funding; Grifols: Consultancy, Honoraria, Research Funding. Costa: Grifols: Current Employment, Other: Grifols is a manufacturer of the pdFVIII/VWF concentrate, Fanhdi®. Willis: Grifols: Current Employment, Other: Grifols is a manufacturer of the pdFVIII/VWF concentrate, Fanhdi®.

Antithrombotic Effect of a Recombinant von Willebrand Factor, VCL, on Nitrogen Laser-Induced Thrombus Formation in Guinea Pig Mesenteric Arteries

1995 ◽  
Vol 73 (02) ◽  
pp. 318-323 ◽  
Author(s):  
K Azzam ◽  
L I Garfinkel ◽  
C Bal dit Sollier ◽  
M Cisse Thiam ◽  
L Drouet
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Mesenteric Arteries ◽  
Antithrombotic Effects ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryTo assess the antithrombotic effectiveness of blocking the platelet glycoprotein (GP) Ib/IX receptor for von Willebrand factor (vWF), the antiaggregating and antithrombotic effects were studied in guinea pigs using a recombinant fragment of vWF, Leu 504-Lys 728 with a single intrachain disulfide bond linking residues Cys 509-Cys 695. The inhibitory effect of this peptide, named VCL, was tested in vitro on ristocetin- and botrocetin-induced platelet aggregation and compared to the ADP-induced platelet aggregation. In vivo, the antithrombotic effect of VCL was tested in a model of laser-injured mesentery small arteries and correlated to the ex vivo ristocetin-induced platelet aggregation. In this model of laser-induced thrombus formation, five mesenteric arteries were studied in each animal, and the number of recurrent thrombi during 15 min, the time to visualization and time to formation of first thrombus were recorded.In vitro, VCL totally abolished ristocetin- and botrocetin-induced platelet aggregation, but had no effect on ADP-induced platelet aggregation. Ex vivo, VCL (0.5 to 2 mg/kg) administered as a bolus i. v. injection inhibits ristocetin-induced platelet aggregation with a duration of action exceeding 1 h. The maximum inhibition was observed 5 min after injection of VCL and was dose related. The same doses of VCL had no significant effect on platelet count and bleeding time. In vivo, VCL (0.5 to 2 mg/kg) had no effect on the appearance of the thrombi formed but produced dose-dependent inhibition of the mean number of recurrent thrombi (the maximal effect was obtained at 5 min following i. v. injection of the highest dose: 0.8 ± 0.2 thrombi versus 4 ± 0.4 thrombi in controls). The three doses of VCL increased the time in which the first thrombus in a concentration-dependent manner was formed. However, the time to visualize the first thrombus was only prolonged in the higher dose-treated group.These in-vivo studies confirm that VCL induces immediate, potent, and transient antithrombotic effects. Most importantly, this inhibition was achieved without inducing thrombocytopenia nor prolongation of the bleeding time.

N-Acetyl Cysteine Reduces von Willebrand Factor Multimer Size In Vitro and In Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 420-420
Author(s):  
Junmei Chen ◽  
Francisca C. Gushiken ◽  
Leticia Nolasco ◽  
Joel F. Moake ◽  
Jose A. Lopez
Keyword(s):  
Von Willebrand Factor ◽  
Chronic Obstructive Lung Disease ◽  
Chronic Obstructive ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Acetyl Cysteine ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract von Willebrand factor (VWF) shares a similar domain structure with many polymeric mucins, including the presence of D domains and a C-terminal cysteine knot, which allows these molecules to form polymeric structures that can reach immense sizes. Precipitation of polymeric lung mucins complicates the clinical course of cystic fibrosis and chronic obstructive lung disease, and in both cases the viscosity of the inspissated mucus can be reduced by treatment with N-acetyl cysteine (NAC), which presumably reduces the size of the mucin polymers by reducing sensitive disulfide bonds. Because of the similarity of VWF and mucin multimers, we examined whether NAC could also reduce VWF multimer size both in vitro and in vivo. In vitro, we incubated NAC at different concentrations and for different times with ultra-large VWF multimers (ULVWF) isolated from endothelial cell supernatant and examined the effect on multimer size using agarose gel electrophoresis. NAC reduced ULVWF size in a time- and concentration-dependent manner, with the peak effect reached at 5 min and at concentration of 0.5 mM. We then examined the effect of NAC on ULVWF/platelet “strings” formed on the surface of histamine-activated endothelial cells by perfusing the strings with NAC solutions. At 1 mM, NAC eliminated almost all of the adherent strings within 5 minutes. We next examined the effect of NAC in vivo by following VWF multimer size with time in C57B/6 injected with NAC either intraperitoneally or intravenously. NAC, at a single dose of 500 mg/kg, induced a sustained reduction in VWF multimer size in the treated mice within 4 hours after injection. The effects lasted up to 8 hours. These results suggest that NAC may be a rapid, safe, and effective treatment for patients suspected of suffering from thrombotic thrombocytopenic purpura, a disorder characterized by a failure to process ULVWF.

Effect of 3-Phenyl-2-Propene-1-ol on PGE2Release from Rat Cerebral Microvascular Endothelial Cells Stimulated by IL-1β

2006 ◽  
Vol 34 (04) ◽  
pp. 685-693 ◽  
Author(s):  
Jian-You Guo ◽  
Hai-Ru Huo ◽  
Bao-Sheng Zhao ◽  
Hong-Bin Liu ◽  
Lan-Fang Li ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cultured Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Antipyretic Effect ◽  
Positive Immunoreactivity ◽  
Von Willebrand ◽  
Willebrand Factor

Fever, an elevation in body temperature, is thought to be terminally mediated by prostaglandin E2(PGE2). Both Guizhi Tang (GZT) and its active fraction A (Fr.A) showed an antipyretic effect in rats. 3-Phenyl-2-propene-1-ol was one of the active compounds isolated from Fr.A. In the present study, we examined the influence of interleukin-1β (IL-1β) on prostaglandin E2(PGE2) release, and the effect of 3-phenyl-2-propene-1-ol on IL-1β-induced PGE2release from rat cerebral endothelial cells (rCMEC). Cultured rCMEC were used in the study. In vitro, cells express typical phenotypic markers of brain endothelium. Using a monoclonal antibody against von Willebrand factor, immunocytochemical analysis revealed positive immunoreactivity in the cytoplasm of cultured cells. rCMEC were incubated in M199 medium containing IL-1β in the presence or absence of 3-phenyl-2-propene-1-ol. After incubation, the conditioned media were collected and the amount of PGE2was measured by enzyme-linked immunosorbent assay (ELISA). IL-1β increased the production of PGE2in a dose- and time-dependent manner. 3-Phenyl-2-propene-1-ol significantly decreased IL-1β-induced PGE2release in a dose-dependent manner. Our results indicate that 3-phenyl-2-propene-1-ol inhibits the PGE2release from rCMEC stimulated by IL-1β, and may have an antipyretic effect.

Is group O platelet hemostatic activity reduced?

2020 ◽  
Author(s):  
Х.С. Танкаева ◽  
Е.А. Шестаков ◽  
В.Я. Мельниченко ◽  
Е.Б. Жибурт
Keyword(s):  
Blood Group ◽  
Von Willebrand Factor ◽  
Platelet Transfusion ◽  
Clinical Effectiveness ◽  
Abo Blood Group ◽  
Hemostatic Activity ◽  
Shift Model ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Kinetics Of

Введение: В 2019 г. опубликованы полученные в модели артериального сдвига доказательства более слабой связи с фактором Виллебранда тромбоцитов группы О: у не-О тромбоцитов кинетика этой связи на 40% выше. Высказано предположение о меньшей гемостатической эффективности переливания этих тромбоцитов. Цель исследования: сопоставить клиническую эффективность переливания тромбоцитов группы О и других фенотипов системы группы крови АВО (не-О). Материалы и методы: У 310 пациентов проведено 674 переливания тромбоцитов. Анализировали и оценивали клиническую эффективность переливания двух групп тромбоцитов различных фенотипов системы группы крови АВО: О (n = 290) и не-О (n = 384). Результаты: При переливании О-тромбоцитов реципиентам реже требовались последующие трансфузии, а интервал до следующей трансфузии в среднем был на 21,7% больше, чем при переливании не-О тромбоцитов. После переливания О-тромбоцитов и не-О тромбоцитов не выявлено различий в концентрации тромбоцитов в крови реципиентов до переливания и спустя 20 ч. При переливании О-тромбоцитов наблюдали более высокий абсолютный прирост тромбоцитов в крови реципиентов, однако скорректированный прирост тромбоцитов после переливания О и не-О тромбоцитов не различался. Заключение: Таким образом, гипотеза о сниженной гемостатической активности тромбоцитов группы О не подтверждена. Background: In 2019 on arterial shift model the evidence was obtained of a weaker connection of von Willebrand factor and group O-platelets: in non-O platelets the kinetics of this connection was higher by 40%. A hypothesis was suggested that the O-platelet transfusion is hemostatically less effective. Objectives: to compare the clinical effectiveness of O-platelets transfusion and other phenotypes of ABO blood group (non-O). Patients/Methods: In 310 patients, 674 platelet transfusions were performed. Clinical effectiveness of transfusion of two platelet groups with different phenotypes of ABO blood group was analyzed and assessed: O (n = 290) and non-O (n = 384). Results: After O-platelets transfusion, recipients rarely required next transfusions, and the interval until next transfusion was on average 21.7% longer than after non-O platelets transfusion. After transfusion of O-platelets and non-O platelets, there were no differences between platelets concentration in recipient’s blood before transfusion and after 20 hours. After O-platelets transfusion, a higher absolute increment of platelets in recipient’s blood was observed, but the corrected increment of platelets after transfusion of O and non-O platelets did not differ. Conclusions: So, the hypothesis of reduced hemostatic activity of O-platelets is not confirmed.

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