Thromboxane B2 Levels Research Articles

Thromboxane A2 in the paraventricular hypothalamic nucleus mediates glucoprivation-induced adrenomedullary outflow

Glucoprivation stimulates a rapid sympathetic response to release and/or secrete catecholamines into the bloodstream. However, the central regulatory mechanisms involving adrenoceptors and prostanoids production in the paraventricular hypothalamic nucleus (PVN) that are responsible for the glucoprivation-induced elevation of plasma catecholamines are still unresolved. In this study, we aimed to clarify whether glucoprivation-induced activation of noradrenergic neurons projecting to the PVN can induce α- and/or β-adrenergic receptor activation and prostanoids production in the PVN to elevate plasma catecholamine levels. We examined the effects of α- and β-adrenergic receptor antagonists, a cyclooxygenase inhibitor, a thromboxane A synthase inhibitor, and a PGE2 subtype EP3 receptor antagonist on intravenously administered 2-deoxy-D-glucose (2-DG)-induced elevation of noradrenaline in the PVN and plasma levels of catecholamine in freely moving rats. In addition, we examined whether intravenously administered 2-DG can increase prostanoids levels in the PVN microdialysates. Intracerebroventricular (i.c.v.) pretreatment with phentolamine (a non-selective α-adrenergic receptor antagonist) suppressed the 2-DG-induced increase in the plasma level of adrenaline, whereas i.c.v. pretreatment with propranolol (a non-selective β-adrenergic receptor antagonist) suppressed the 2-DG-induced elevation of the plasma level of noradrenaline. I.c.v. pretreatment with indomethacin (a cyclooxygenase inhibitor) and furegrelate (a thromboxane synthase inhibitor) attenuated the 2-DG-induced elevations of both noradrenaline and adrenaline levels. Furthermore, 2-DG administration elevated the thromboxane B2 level, a metabolite of thromboxane A2 in PVN microdialysates. Our results suggest that glucoprivation-induced activation of α- and β-adrenergic receptor in the brain including the PVN and then thromboxane A2 production in the PVN, which are essential for the 2-DG-induced elevations of both plasma adrenaline and noradrenaline levels.

Correlation study between the pharmacokinetics of seven main active ingredients of Mahuang decoction and its pharmacodynamics in asthmatic rats

The aim of this study was to investigate the pharmacokinetics and pharmacodynamics of seven main active components of Mahuang decoction (MHD) and its time-concentration-effect relationship. The asthmatic rat model was established by the method of ovalbumin (OVA) sensttization. The plasma concentrations of ephedrine, pseudoephedrine, methylephedrine, amygdalin, liquiritin, cinnamic acid, glycyrrhizic acid in asthmatic model rat were investigated by a selective and rapid HPLC/MS-MS method. Simultaneously, the asthma-involved cytokines including leukotrienes B4 (LTB4), thromboxane B2 (TXB2), 6-Keto-Prostaglandin F1α (6-K-PGF1α) and histamine (HIS) levels in rat plasma were determined by using ELISA. A mathematics method was applied to assess the trend of percentage rate of change among different time intervals of the seven components. The sigmoid E max function was used to establish the PK-PD modeling of MHD. The results indicated that MHD could control or ameliorate asthma. There was a hysteresis between the peaked drug concentration and maximum therapeutic effect of MHD. The PK-PD curves of MHD showed clockwise or counter-clockwise hysteresis loop. In addition, amygdalin might exert a more significant influence on regulating cytokines levels in asthmatic rats among the seven components of MHD.

Older adults with frailty syndrome present an altered platelet function and an increased level of circulating oxidative stress and mitochondrial dysfunction biomarker GDF-15

IntroductionThe elderly population is increasing worldwide and in Chile, it is expected to grow rapidly. The World Health Organization (WHO) ICOPE guideline (Integrated Care for Older People) emphasizes the importance of frailty diagnosis to prevent dependence. Frailty in older adults is considered an indicator of vulnerability and poor health outcomes, of multifactorial etiology. Our objective was to investigate the association of activation of coagulation and increased risk of thrombosis with frailty in people older than 64 years. A prevalent-case control study was designed with 28 frail older and 27 robust older adults (non-frail, control group) older than 64 years. Frailty was defined by Fried's Phenotype, Platelet aggregation and activation plasma levels of Thromboxane B2 (TXB2), 8-isoprostane and Growth Differentiation Factor-15 (GDF-15) were determined. ResultsCompared to healthy controls, frail older adults, had a) higher percentage of platelet aggregation induction with ADP 4 μM (82.85% (3.35) and 73.41% (3.26), p-value = 0.024) and subaggregant dose of ADP (30.83% (7.47) and 13.25% (3.21), p-value = 0.002); b) higher platelet activation: P-selectin exposure (18.23% (4.41) and 6.96% (1.08), p-value = 0.011), and activated GPIIβ-IIIα (21.51% (3.41) and 8.26% (1.18), p-value = 0.001), at the baseline level and against a subaggregant dose ADP: P-selectin exposure (46.93% (5.95) and 13.41% (3.35), p-value = 0.002) and activated GPIIβ-IIIα (43.29% (6.04) and 26.71% (4.92), p-value = 0.024); c) higher plasma levels of TXB2 (201.8 ng/mL (59.53–236.3) and 45.77 ng/mL (25.14–98.26), p-value<0.0001), d) elevated plasma levels of 8-isoprostane (70.94 pg/mL, IQ: 65.89–99,96 and 56.24 pg/mL, IQ: 42.18–74.81, p-value = 0.001), and e) higher plasma GDF-15 levels (2,379 pg/mL, IQ: 1,845–4,121and 1367 pg/mL, IQ: 1190–1747, p-value = 0.0001). DiscussionOlder adults with frailty syndrome have an upregulated platelet activity that may contribute to an increased risk of thrombosis and aspirin resistance. The elevated oxidative stress and increases of GDF-15 levels might be related to altered platelet responsiveness in frail patients. ConclusionThe determination of biomarkers of platelet dysfunction, oxidative stress and cell senescence/mitochondrial dysfunction may contribute to frailty diagnosis, and approaches aimed at regulating platelet function in frail older adults could contribute to its prevention and treatment.

The relationship of a Prothrombin G20210A mutation or a factor V Leiden mutation and on-aspirin platelet (re-)activity.

The interplay between platelets and pro-thrombotic factors may have been under-investigated in the identification of aspirin users at high risk for cardiovascular event reoccurrences. There is growing evidence that a Prothrombin G20210A (FII) or a Factor V Leiden (FVL) mutation might increase platelet activity. Subsequently, this study assessed on-aspirin platelet (re-)activity in non-pregnant participants with a FII - or a FVL mutation in comparison with non-pregnant data derived from controls. This study was conducted with data derived from the follow-up FRUIT-RCT. This is a unique cohort namely, participants without a history of cardiovascular disease or thrombotic events, but who are a carrier of a pro-thrombotic mutation. All participants were instructed to ingest aspirin once daily for 10days. Platelet (re-)activity was measured by the PFA Closure Time (PFA-CT), the VerifyNow (VN-ARU), and serum Thromboxane B2 (sTxB2) levels. In total, eight participants with a FII-, 15 with a FVL mutation, and 21 controls were included. The FII mutation carriers demonstrated significantly higher on-aspirin platelet (re)-activity (PFA-CT, -92sec.; VN-ARU, +37 ARU) vs. controls. The FVL carriers demonstrated similar on-aspirin platelet (re-)activity vs. controls. The sTxB 2 levels were similar in either of the carrier groups vs. controls. We feel these data are suggestive of increased on-aspirin platelet (re-)activity, as measured by the PFA-200 and the VerifyNow, in non-pregnant carriers of a FII-mutation, but not in carriers of FVL-mutation. Interestingly, this increased on-aspirin platelet (re-)activity is present in spite of low sTxB2 levels.

Pyruvate Protects Against Intestinal Injury by Inhibiting the JAK/STAT Signaling Pathway in Rats With Hemorrhagic Shock

BackgroundThis study aimed to investigate the role of Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway in protection by peritoneal resuscitation (PR) using pyruvate-peritoneal dialysis solution (PY-PDS) against intestinal injury from hemorrhagic shock (HS) in rats. Materials and MethodsSixty-four rats were assigned to eight groups: group SHAM; group intravenous resuscitation (VR); groups NS, LA, and PY in which the rats were subjected to HS and PR with normal saline (NS), lactate-peritoneal dialysis solution (LA-PDS), and PY-PDS, respectively, combined with VR; and groups DMSO, RPM, and AG490 in which the rats were subjected to HS and VR with pretreatment of dimethyl sulfoxide (DMSO), rapamycin (RPM), and tyrphostin B42 (AG490). ResultsAt 2 h after HS and resuscitation, the levels of diamine oxidase, 15-F2t-isoprostane, thromboxane B2, and endothelin-1, in the blood and the intestinal mucosal apoptotic index and caspase-3 were lower in groups PY, RPM, and AG490 than in groups VR, NS, LA, and DMSO. Group PY showed lower levels of malondialdehyde and myeloperoxidase and a higher level of superoxide dismutase than groups VR, NS, and LA. Phosphorylated JAK2 and phosphorylated STAT3 levels were lower in groups PY, RPM, AG490, and LA than in groups VR, NS, and DMSO. ConclusionsThe protection mechanism of PR with PY-PDS combined with VR was related to the inhibition of the JAK/STAT signaling pathway during HS and resuscitation. The process might include suppression of oxidative stress, reduction of neutrophil infiltration, regulation of microcirculation, and inhibition of apoptosis.

Effect of low-dose aspirin on platelet aggregation inhibition in patients with rheumatoid arthritis

Introduction : The risk for coronary artery disease (CAD) and mortality has increased in patients with rheumatoid arthritis (RA). Aspirin has anti-thrombotic effects and causes reduction in CAD occurrence in high-risk individuals. The objective of present project was evaluating the influence of low-dose aspirin on inhibition of platelet aggregation in patients with RA. Methods: Forty-eight subjects with RA diagnosed based on the American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) 2010 criteria and age- and sex-matched healthy participants were studied. All subjects received 81 mg/day aspirin for 10 days. Level of the serum thromboxane B2 (sTxB2), a permanent metabolite of thromboxane A2 (TxA2), was measured before and after therapy using enzyme-linked immunosorbent assay (ELISA) kit. The impotency to decrease sTxB2 production to less than 10 ng/ml indicates suboptimal suppression of platelet aggregation via aspirin. Results: Low-dose aspirin decreased sTxB2 significantly compared with baseline in patients with RA [median interquartile range (IQR): 25.72 (11.78, 90.10) to 7.74 (5.80, 8.82), P &lt; 0.001] and in healthy controls [median (IQR): 40.50 (33.25, 50.90) to 7.30 (4.75, 8.85), P &lt; 0.001]. No remarkable changes were seen in sTxB2 between patients and controls after adjustment (P &gt; 0.050). Pharmacologic influence of aspirin was suboptimal in 6.25% of cases in the presence of higher erythrocyte sedimentation rate (ESR) and in 2.7% of controls. Low-dose aspirin decreased sTxB2 significantly only in patients with Framingham Risk Score (FRS) &lt; 10%. Conclusion: Low-dose aspirin decreased sTxB2 level and suppressed platelet aggregation and therefore, was effective in primary prevention of cardiovascular (CV) events in patients with RA; however, additional studies are required to reach accurate conclusions.

Resistance of aspirin during and after pregnancy: A longitudinal cohort study.

The objective of this study is to investigate possible changes in aspirin resistance during and after pregnancy over time. A longitudinal cohort study in obstetric high risk women with an indication for aspirin usage during pregnancy to prevent placenta mediated pregnancy complications. Aspirin resistance measured in the first, second and third trimester of pregnancy and at least three months postpartum by four complementary test: PFA-200, VerifyNow®, Chronolog light transmission aggregometry (Chronolog LTA) and serum thromboxane B2 (TxB2) level measurements. Correlation between the devices was investigated. In total, 23 pregnant women participated in the present study. Aspirin resistance according to the PFA-200, VerifyNow®, Chronolog LTA and serum TxB2, was 30.4%, 17.4%, 26.1% and 23.8% respectively. Resistance by any device was 69.6%. Aspirin resistance measured by the VerifyNow®, Chronolog LTA, serum TxB2 and aspirin resistance by any device during pregnancy was demonstrated more frequently than aspirin resistance after pregnancy. Correlation between the different devices was weak. Aspirin resistance was found in a considerable part of the participants. Considerable variation between participants, within participants over time and between the different devices was found. Prevalence of aspirin resistance during pregnancy differs from after pregnancy. More research on aspirin resistance and clinical obstetric outcome is needed.

Coagulant Effects and Mechanism of Schefflera heptaphylla (L.) Frodin.

Schefflera heptaphylla (L.) Frodin, are commonly used in anti-inflammatory, analgesic, traumatic bleeding and hemostasisas. In this paper, the coagulation effect of the ethanol extract (Set), ethyl acetate phase (Sea) and n-butanol phase (Sbu) was evaluated by prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen content (FIB) assays in vitro. Then, Three main lupanine triterpenes (compounds A–C) were isolated and identified from Sea and Sbu by a bioassay-guided method and their structure were identified as 3α-Hydroxy-lup-20(29)-ene-23, 28-dioic acid, betulinic acid 3-O-sulfate and 3α-Hydroxy-lup-20(29)-ene-23, 28-dioic acid 28-O-(α-l-rhamnopyranosyl(1→4)-O-β-d-glucopyranosyl(1→6))-β-d-glucopyranoside) by spectroscopic data analysis. Among of them, compound B was confirmed to have significant coagulant effect in vitro. Furthermore, the pro-coagulation mechanism of S. heptaphylla extracts and compound B were investigated by measuring whole blood viscosity (WBV), plasma viscosity (PV), erythrocyte sedimentetion rate (ESR), pack cell volume (PCV), APTT, PT, TT, and FIB in vivo. Meanwhile, the levels of thromboxane B2 (TXB2), 6-keto prostaglandin F1α (6-keto-PGF1α), endothelial nitric oxide synthase (eNOS) and (endothelin-1) ET-1 were detected. The bleeding time (BT) was tested by tail bleeding method, which proved the traumatic bleeding and hemostasis activities of S. heptaphylla. The pharmacology experiments showed that the Set, Sea, Sbu and compound B has significant pro-coagulation effect. In addition, compound B might be the main constituent of pro-coagulation in S. heptaphylla These results could support the fact that S. heptaphylla could be used traditionally to cure traumatic bleeding, and the pro-coagulation effects were associated with the regulation of vascular endothelium active substance and hemorheology parameters.

Pathophysiological role of prostanoids in coagulation of the portal venous system in liver cirrhosis.

BackgroundProstanoids are important regulators of platelet aggregation and thrombotic arterial diseases. Their involvement in the development of portal vein thrombosis, frequent in decompensated liver cirrhosis, is still not investigated.MethodsTherefore, we used pro-thrombotic venous milieu generation by bare metal stent transjugular intrahepatic portosystemic shunt insertion, to study the role of prostanoids in decompensated liver cirrhosis. Here, 89 patients receiving transjugular intrahepatic portosystemic shunt insertion were included in the study, and baseline levels of thromboxane B2, prostaglandin D2 and prostaglandin E2 were measured in the portal and the hepatic vein.ResultsWhile the hepatic vein contained higher levels of thromboxane B2 than the portal vein, levels of prostaglandin E2 and D2 were higher in the portal vein (all P<0.0001). Baseline concentrations of thromboxane B2 in the portal vein were independently associated with an increase of portal hepatic venous pressure gradient during short term follow-up, as an indirect sign of thrombogenic potential (multivariable P = 0.004). Moreover, severity of liver disease was inversely correlated with portal as well as hepatic vein levels of prostaglandin D2 and E2 (all P<0.0001).ConclusionsElevated portal venous thromboxane B2 concentrations are possibly associated with the extent of thrombogenic potential in patients with decompensated liver cirrhosis.Trial registrationClinicalTrials.gov identifier: NCT03584204.

Protective effects and potential mechanism of salvianolic acid B on sodium laurate-induced thromboangiitis obliterans in rats

BackgroundThe root of Salvia miltiorrhiza f. alba (RSMA) (Lamiaceae) is used for the treatment of patients with thromboangiitis obliterans (TAO) in traditional Chinese medicine. Previously, a mixture of phenolic acids extracted from RSMA has shown significant protective effects on TAO rats. PurposeThis study investigates the inhibitory effects of salvianolic acid B on TAO induced by sodium laurate injection in rats to explore the effective constituents of RSMA in TAO treatment. MethodsTAO rats were developed using injected sodium laurate. After treatment with ligustrazine hydrochloride (15 mg/kg) and various doses of salvianolic acid B (10, 20, 40 mg/kg) by tail intravenous injection, levels of thromboxane B2 (TXB2), 6-keto-prostaglandin F1α (6-keto-PGF1α) and endothelin-1 (ET-1) in plasma were determined using enzyme-linked immunosorbent assay. The right femoral arteries were studied by hematoxylin and eosin staining and immunohistochemical analysis to determine pathological changes and overexpression of tumor necrosis factor (TNF)–α and inducible nitric oxide synthase (iNOS) in the femoral artery walls of TAO rats. ResultsSalvianolic acid B significantly decreased the expressions of TXB2 and ET-1 and increased the expression of 6-keto-PGF1α in plasma, and significantly inhibited the overexpression of TNF-α and iNOS in the femoral artery walls of TAO rats at medium and high doses. ConclusionSalvianolic acid B has a protective effect on TAO rats. The mechanism may involve inhibition of thrombosis and TAO-associated inflammatory responses, which may explain the success of RSMA treatment of TAO in humans in traditional Chinese medical practice. Hence, it may be a potential drug for TAO treatment in conventional medicine.

P2245Sex differences in the in-vivo markers of platelet activation among patients with ischemic heart disease: insights from the EVA study

Abstract Background/Introduction Ischemic heart diseases (IHD) are not synonymous with obstructive flow-limiting coronary artery disease (CAD), especially in women. Platelet dysfunction is suggested as a potential mechanism favouring ischemia in non-obstructive CAD. However, it is unknown whether sex differences in platelet function of patients with non-obstructive CAD exist. Purpose We assessed for sex differences in in-vivo markers of platelet activation among patients with the acute coronary syndrome and chronic stable angina, with or without obstructive CAD Methods From the “Endocrine Vascular disease Approach” (EVA) study, we selected IHD patients undergoing urgent or elective coronary angiography with complete baseline clinical characteristics and angiographic data. Non-obstructive CAD was defined as the presence of coronary stenosis &lt;50%. Thromboxane B2 (TxB2) and soluble P-selectin (sP-s) were measured at baseline. A sex-stratified analysis of platelet biomarkers was performed. Results Among two-hundred-seventy-seven patients (mean age 67±11, 37% women), non-obstructive CAD was documented in 25% of patients. Acute coronary syndrome (ACS) was the reason for angiography in 61% of cases. Women had more frequently ACS, as compared with men (54.8% vs 41.3%, p=0.001), with predominantly non-obstructive CAD. Median serum TxB2 (121.5 [92.7–174.0] vs 103.5 [83.0–140.2] pg/ml, p=0.005) and plasma sP-s (27.0 [18.7–35.0] vs 22.0 [16.0–30.0] ng/ml, p=0.006) levels were higher in patients with ACS as compared with the ones with stable chronic angina. The median concentration of TxB2 was significantly increased in women as compared with men, regardless of the clinical presentation and the coronary stenosis degree (all comparison, p&lt;0.001). However, women with non-obstructive CAD were the group with the highest serum levels of TxB2 (140.0 [111.0–152.0] pg/ml). Sex differences in the plasma sP-s level were also observed among patients with stable chronic angina (women, 26 [20.0–34.0] vs men, 21 [16.6–27.7] ng/ml, p=0.002) and with non-obstructive CAD (women, 26 [20.5–34.5] vs men, 18.5 [16.6–26.0] ng/ml, p=0.003). Conclusion(s) Women with IHD and non-obstructive CAD had increased level of TxB2 and sP-s as compared with men, independently by the clinical presentation. Further investigations are warranted to verify the role of platelet hyperactivation in the pathogenesis of myocardial ischemia with non-obstructive coronary artery disease among women. Acknowledgement/Funding Scientific Independence of Young Researchers Program (RBSI14HNVT) - Ministry of Education, University and Research (MIUR)

P1935Pharmacokinetic and pharmacodynamic assessment of a lipid-based aspirin formulation: results of a prospective, randomised, crossover study

Abstract Objectives Aspirin, or acetylsalicylic acid (ASA), can lead to gastrointestinal mucosal injury through disruption of its protective phospholipid bilayer, underscoring the need for ASA formulations with a more favorable safety profile while maintaining an effective pharmacologic profile. A liquid formulation using a novel pharmaceutical lipid aspirin complex (PL-ASA) has been designed to prevent the disruption of the protective mucosal bilayer. We sought to determine the pharmacokinetic (PK)/pharmacodynamic (PD) characteristics of PL-ASA compared with traditional, immediate release aspirin (IR-ASA). Methods In this active-control crossover study, 16 healthy volunteers were randomized to receive a single dose of either IR-ASA 325 mg or PL-ASA 325 mg in a sequential fashion with a 2-week washout period between treatment assignments. The primary objectives of the study were to assess PK (i.e., plasma salicylic acid levels) and PD (i.e., serum thromboxane B2 levels) bioequivalence over a 24–hour period after drug administration, of PL-ASA and IR-ASA using established criteria. Results The PK parameter values were similar for PL-ASA and IR-ASA, with median AUC 0-t and Cmax values nominally higher for PL-ASA. Log-transformed PK parameters meeting FDA-criteria for bioequivalence (80% to 125%) are provided in the Table. Serum thromboxane B2 levels were similar for PL-ASA and IR-ASA, with Cmin values below 3.1 ng/mL (cut-off associated with decreased cardiovascular events) for both drugs. Both drugs also showed &gt;99% inhibition of serum thromboxane B2 levels (≥95% inhibition represents the cut-off to define aspirin responders). Several secondary PK/PD parameters showed similarities between the two drugs (data not shown). Overall, these findings support functional and clinical equivalence between PL-ASA and IR-ASA. PK Results Parameter Ratio (PL-ASA/IR-ASA) 90% Confidence Interval AUC0-t 96.51 89.24, 104.37 Cmax 103.73 92.06, 116.89 Conclusions PL-ASA's novel liquid formulation has similar PK and PD performance compared with IR-ASA. The improved endoscopic safety profile of PL-ASA coupled with its pharmacologic efficacy equivalent to IR-ASA may result in an improved benefit-risk performance, warranting evaluation in future trials. Acknowledgement/Funding PLx Pharma, Inc.

YiqiHuoxue Decoction and Its Ethanol Precipitation Show Anti-Platelet and Antithrombotic Effects by Suppressing Thromboxane B2 Formation.

YiqiHuoxue decoction (YHD) is frequently prescribed to prevent and treat cardiovascular diseases. YHD inhibits platelet aggregation, however the underlying mechanisms are unclear. The in vitro and in vivo anti-platelet and antithrombotic effects of YHD and ethanol-precipitated YHD (EYHD) and underlying mechanisms were investigated. Forty-six Sprague-Dawley (SD) rats and 36 male Kunming mice were examined. Ten SD rats were used to assess the cytotoxicity of YHD and EYHD by releasing lactate dehydrogenase from treated platelets. The remaining 36 SD rats were divided into six groups (six per group), including control saline (5 mL/kg), aspirin (20 mg/kg), YHD low dosage (0.2 g/kg), YHD high dosage (2.0 g/kg), 75% EYHD low dosage (0.2 g/kg), and 75% EYHD high dosage (2.0 g/kg) groups to detect platelet aggregation; the 36 Kunming mice were divided into 6 groups to detect mesenteric arterial thrombosis induction. Thromboxane B2 (TXB2) levels were determined by enzyme immunoassay. YHD high dosage and 75% EYHD (low and high dosage) inhibited ADP-induced platelet aggregation. Moreover, collagen-induced platelet aggregation was significantly suppressed by YHD (high dosage), 75% EYHD (high dosage), and 75% EYHD (low dose). Rats given 75% EYHD (high dose) displayed a marked reduction in collagen-induced platelet aggregation at 2 h post-administration. YHD and EYHD markedly prolonged the onset of thrombosis causing loose attachment of the thrombus to the vascular endothelium, but bleeding and clotting times were not significantly changed. Finally, YHD and EYHD markedly reduced TXB2 levels. YHD and EYHD effectively inhibit platelet activation and thrombosis, presumably by suppressing TXB2.

Effects of functionalized silver nanoparticles on aggregation of human blood platelets.

PurposeWe studied the effects of silver nanoparticles (AgNPs) on human blood platelet function. We hypothesized that AgNPs, a known antimicrobial agent, can be used as blood-compatible, “ideal material’’ in medical devices or as a drug delivery system. Therefore, the aim of the current study was to investigate if functionalized AgNPs affect platelet function and platelets as well as endothelial cell viability in vitro.Methods AgNPs, functionalized with reduced glutathione (GSH), polyethylene glycol (PEG) and lipoic acid (LA) were synthesized. Quartz crystal microbalance with dissipation was used to measure the effect of AgNPs on platelet aggregation. Platelet aggregation was measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast microscopy. Flow cytometry was used to detect surface abundance of platelet receptors. Lactate dehydrogenase test was used to assess the potential cytotoxicity of AgNPs on human blood platelets, endothelial cells, and fibroblasts. Commercially available ELISA tests were used to measure the levels of thromboxane B2 and metalloproteinases (MMP-1, MMP-2) released by platelets as markers of platelet activation.Results2 nm AgNPs-GSH, 3.7 nm AgNPs-PEG both at 50 and 100 µg/mL, and 2.5 nm AgNPs-LA at 100 µg/mL reduced platelet aggregation, inhibited collagen-mediated increase in total P-selectin and GPIIb/IIIa, TXB2 formation, MMP-1, and MMP-2 release. The tested AgNPs concentrations were not cytotoxic as they did not affect, platelet, endothelial cell, or fibroblast viability.ConclusionAll tested functionalized AgNPs inhibited platelet aggregation at nontoxic concentrations. Therefore, functionalized AgNPs can be used as an antiplatelet agent or in design and manufacturing of blood-facing medical devices, such as vascular grafts, stents, heart valves, and catheters.

Clinical study of Yiqi-Jiedu decoction combined with mesalazine sustained release granules for the patients with ulcerative colitis

Objective To evaluate the effect of Yiqi-Jiedu decoction combined with mesalazine sustained release granules for the patients with ulcerative colitis (UC). Methods A total of 93 UC patients who met the inclusion criteria were divided into control group (46 cases) and study group (47 cases) according to the random number table method. The control group was treated with mesalazine sustained release granules orally. The treatment group added Yiqi-Jiedu decoction on the basis of the control group. Both groups were treated for 2 months. The level of plasma thromboxane B2 (TXB2), 6-keto-prostaglandin F1α (6-Keto-PGF1α) and serum CRP, IL-1 and TNF-α were measured by ELISA, and the clinical effect was evaluated. Results The total effective rate was 95.7% (45/47) in the treatment group and 78.3% (36/46) in the control group. There was significant difference between the two groups (χ2=6.323, P=0.012). After treatment, the plasma TXB2 level in the treatment group was significantly lower than that in the control group (601.14 ± 13.31 pg/ml vs. 780.33 ± 16.54 pg/ml; t=57.619, P<0.01), and the plasma 6-Keto-PGF1α level was significantly higher than that in the control group (84.04 ± 11.39 pg/ml vs. 69.48 ± 10.21 pg/ml; t=6.487, P<0.01). After treatment, the level of CRP, IL-1 and TNF-α in the treatment group was significantly lower than those in the control group (t=15.457, 7.006 and 17.434, respectively, all Ps<0.01). Conclusions The Yiqi-Jiedu decoction combined with mesalazine sustained release granules can reduce the level of serum inflammatory cytokines in UC patients, reduce the level of plasma TXB2, and increase the level of plasma 6-Keto-PGF1α, so as to improve the clinical effectiveness. Key words: Colitis, ulcerative; Yiqi-Jiedu decoction; Inflammation; Therapies, investigational

A possible relationship between Thromboxane B2 and Leukotriene B4 and the encapsulation of Dirofilaria repens worms in human subcutaneous dirofilariasis

Human subcutaneous dirofilariosis has several clinical presentations. Many cases present as subcutaneous nodules, as a consequence of a local inflammatory reaction that encapsulates and destroys the worms. In addition, there are cases in which migrating worms located in the ocular area remain unencapsulated. In the present work, the levels of two pro-inflammatory eicosanoids, thromboxane B2 (TxB2) and leukotriene B4 (LTB4) are analysed by commercial Enzime-Linked immunosorbent assay (ELISA) in serum samples from 43 individuals, 28 diagnosed as having subcutaneous dirofilariasis presenting a subcutaneous nodule, five diagnosed as having dirofilariasis, in which the worms remained unencapsulated in the periphery of the eye, and ten healthy individuals living in a non-endemic area, used as controls. The worms were surgically removed, identifying Dirofilaria repens as the causative agent in all cases, by Polymerase Chain Reaction (PCR). Individuals with nodules showed significantly higher levels of TxB2 and LTB4 than healthy controls, whereas significant differences in LTB4 levels were observed between individuals with unencapsulated worms and healthy controls. It is speculated that the absence of LTB4 may contribute to the fact that worms remain unencapsulated as a part of immune evasion mechanisms.

Liposome-induced hypersensitivity reactions: Risk reduction by design of safe infusion protocols in pigs

Intravenous administration of liposomal drugs can entail infusion reactions, also known as hypersensitivity reactions (HSRs), that can be severe and sometimes life-threatening in a small portion of patients. One empirical approach to prevent these reactions consists of lowering the infusion speed and extending the infusion time of the drug. However, different liposomal drugs have different levels of reactogenicity, which means that the optimal protocol for each liposomal drug may differ and should be identified and evaluated to make the treatment as safe and convenient as possible.The goal of the present study was to explore the use of pigs for the above purpose, using PEGylated liposomal prednisolone (PLP) as a model drug. We compared the reactogenicities of bolus versus infusion protocols involving 2-, 3- and 4-step dose escalations for a clinically relevant total dose, also varying the duration of infusions. The strength of HSRs was measured via continuous recording of hemodynamic parameters and blood thromboxane B2 levels. We showed that bolus administration or rapid infusion of PLP caused transient changes in systemic and pulmonary blood pressure and heart rate, most notably pulmonary hypertension with paralleling rises in plasma thromboxane B2. These adverse responses could be significantly reduced or eliminated by slow infusion of PLP, with the 3-h 3-step dose escalation protocol being the least reactogenic. These data suggest that the pig model enables the development of safe infusion protocols for reactogenic nanomedicines.

The prevent miscarriage effects of Yun Kang oral liquid on threatened abortion rat induced by kidney deficiency and luteum inhibition

Yun Kang oral liquid is a listed proprietary Chinese Medicine. To further evaluate its efficacy, this experiment established a kidney deficiency and luteum inhibition threatened abortion rat model to observe the effects of Yun Kang oral liquid. Sixty pregnant rats were randomly divided into normal control group (NC), model group (MG), dydrogesterone group (DT, 3.02 mg/kg), and Yun Kang oral liquid low-dose group (YK-L, 4 ml/kg), medium dose group (YK-M, 6 ml/kg), high dose group (YK-H, 9 ml/kg), 10 in each group. On the first day of pregnancy, each administration group was treated with the test drug at the prescribed dose every morning, and the NC group and the MG group were given an equal volume of purified water for 10 days; the rats were intragastrically administrated every afternoon, except for the NC group. In addition, the other groups were intragastrically administered with hydroxyurea at a dose of 450 mg/kg for 9 days, and mifepristone was administered at a dose of 4.0 mg/kg on the 10th day. On the 9th day of pregnancy, behavioral signs such as back temperature, grasping force, pain threshold, and autonomic activity were measured in each group. On the 11th day of pregnancy, blood was collected from the abdominal aorta in each group to determine serum levels of estradiol (E2) , progesterone (P) and thromboxane B2 (TXB2) . Ovary and fetal uterus were removed, the number and diameter of embryos were observed, and the ovary and uterus indexes were calculated. Compared with the NC group, the back temperature, grip, pain threshold, number of spontaneous activities, number of embryos, embryo diameter, uterus index and serum E2, P, TXB2 levels in the MG group were decreased significantly (P＜0.05, 0.01). Compared with the MG group, the back temperature, grasping force, number of embryos, embryo diameter and serum E2 and P levels were increased significantly in each dose group (P＜0.05, 0.01); the pain threshold, autonomic activity, and uterus index of YK-M and YK-H group were increased significantly (P＜0.05); serum level of TXB2 in YK-H group were increased significantly (P＜0.05). Yun Kang oral liquid has a clear kidney-filling effect on rats with threatened abortion caused by kidney deficiency-luteal suppression. The mechanism may be related to raising serum E2, P, TXB2 levels, improving kidney deficiency and improving embryo quality.

Obesity is associated with impaired responsiveness to once‐daily low‐dose aspirin and in vivo platelet activation

BackgroundThe prevalence and degree of obesity is rising worldwide, increases cardiovascular risk, modifies body composition and organ function, and potentially affects the pharmacokinetics and/or pharmacodynamics of drugs. ObjectivesTo investigate the pharmacodynamics of once‐daily low‐dose aspirin in healthy obese subjects, and to assess whether body weight (BW) and body mass index (BMI) affect the pharmacology of aspirin. Patients/MethodsOtherwise healthy, obese (BMI > 30 kg/m2) subjects were studied before and after 3‐4 weeks of 100‐mg once‐daily aspirin intake. Aspirin pharmacodynamics were assessed according to serum thromboxane (TX) B2 levels measured at 4 hours, 24 hours (i.e., posologic interval) and 48 hours after the last witnessed intake; age‐matched and sex‐matched non‐obese controls were included. A previously calibrated pharmacokinetic/pharmacodynamic in silico model of aspirin was used to fit serum TXB2 data from obese subjects. At baseline, the major urinary TXA2 and prostacyclin metabolites, urinary isoprostane and plasma inflammatory biomarkers were measured. ResultsIn 16 obese subjects (aged 47 ± 11 years; BMI of 39.4 ± 5.1 kg/m2), residual serum TXB2 values between 4 and 48 hours after aspirin intake were increased 3‐ to 5‐fold as compared with controls. At 24 hours, the residual serum TXB2 level was log‐linearly associated with body size over a wide range of BMI and BW values, without any apparent threshold. The in silico model predicted that reduced aspirin bioavailability would be inversely related to body size and rescued by 200 mg of aspirin once daily or 85 mg twice daily. Baseline urinary TXA2 metabolite, isoprostane and plasma C‐reactive protein levels were significantly increased in obese subjects. ConclusionsObesity is associated with impaired aspirin responsiveness, largely because of body size. Impaired inhibition of platelet activation by conventional low‐dose aspirin may affect antithrombotic efficacy.

Single-dose diclofenac in healthy volunteers can cause decrease in renal perfusion measured by functional magnetic resonance imaging.

We investigated changes of renal perfusion after topical and oral diclofenac administration in healthy volunteers using functional magnetic resonance imaging (MRI) with arterial spin labelling (ASL). Twenty-four healthy human participants (21-51years) underwent 1.5T MRI before and 1h after a single oral dose of diclofenac (50mg). Twelve of 24 participants underwent an additional MRI examination following 3-day topical diclofenac administration. For renal perfusion imaging, a flow-sensitive alternating inversion-recovery TrueFISP ASL sequence was applied. Plasma concentrations of diclofenac and serum concentrations of thromboxane were determined. After oral diclofenac application, large interindividual differences in plasma concentrations were observed (range <3-4604nm). Topical diclofenac application did not result in relevant systemic diclofenac levels (range 5-75nm). MRI showed a significant reduction of renal perfusion in individuals with diclofenac levels ≥225nm (baseline: 347±7 vs diclofenac: 323±8ml/min/100g, P<0.01); no significant differences were observed in participants with diclofenac levels <225nm. Diclofenac levels correlated negatively with thromboxane B2 levels pointing towards target engagement. Single-dose diclofenac caused a decrease in renal perfusion in participants with diclofenac levels ≥225nm. We demonstrated that even a single dose of diclofenac can impair renal perfusion, which could be detrimental in patients with underlying chronic kidney disease or acute kidney injury.