EFFECTIVENESS AND TOLERABILITY OF CV-3988, A SELECTIVE PAF ANTAGONIST, AFTER INTRAVENOUS ADMINISTRATION TO MAN

1987 ◽  
Author(s):  
J Arnout ◽  
A Van Hecken ◽  
I Delepeleire ◽  
Y Miyamoto ◽  
I Holmes ◽  
...  
Keyword(s):  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Biological Activities ◽  
Wide Spectrum ◽  
Platelet Activating Factor ◽  
Controlled Study ◽  
Dependent Manner ◽  
Double Blind ◽  
Health And Disease

Platelet activating factor (PAF) is a naturally occurring phospholipid with a wide spectrum of biological activities. Although PAF has been ascribed a potential role in various conditions including inflammation, asthma, glomerulonephritis and thrombosis, its precise function in physiologic/pathophysiologic processes remains unclear. The introduction of selective PAF receptor antagonists could represent a useful tool to extend our knowledge of the role of this mediator in health and disease.We have investigated the efficacy and tolerability of (RS)-2-methoxy-3-(octadecylcarbomoyloxy)propy1 2-(3-thiazolio)-ethyIphosphate (CV-3988, Takeda Chem. Ind), a selective PAF antagonist with structural analogies with PAF, after intravenous infusion in man in a double-blind, placebo-controlled study. The compound, in doses from 750 to 2,000 pg/kg, significantly reduced platelet sensitivity to PAF. The threshold aggregating concentration (TAC) of PAF was defined as the minimal concentration causing an irreversible aggregation with a maximal amplitude of at least 50% of the difference in light transmission between platelet rich plasma and platelet poor plasma. It increased in a dose-dependent manner reaching 3.6 times the basal TAC (p<0.0005) at the end and 2.60 times the basal TAC (p<0.0005) 4 hours after infusion of the highest dose. The TAC of PAF returned to the basal value within 24 hours after the end of the infusion.CV-3988 did not cause major side effects nor changes in blood pressure, pulse or respiratory rate. However, small but clinically insignificant changes in plasma haemoglobin and serum haptoglobin were seen at the end and four hours after the end of the infusion, indicating a slight haemolysis probably by high local concentrations at the infusion site.Our results indicate that, when adequate infusion volumes and infusion rates are used, CV-3988 can be safely administered to man and should be useful in elucidating the role of PAF in health and disease.

PLATELET-ACTIVATING FACTOR (PAF)-INDUCED INTRACELLULAR Ca MOBILIZATION IN HUMAN PLATELETS.

1987 ◽  
Author(s):  
K Matsuno ◽  
F Katabami ◽  
M Koyama ◽  
K Abe ◽  
K Sakurada ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Human Platelets ◽  
Dependent Manner ◽  
Platelet Suspension ◽  
Fura 2 ◽  
Intracellular Ca ◽  
Specific Antagonist

PAF-induced intracellular Ca2+ mobilization and platelet aggregation were investigated in human platelets. Cytosolic free Ca2+ concentration ([Ca2+]cyt) was measured by using fluorescent 45Ca2+ probe quin2 and fura-2, and photoprotein aequorin. Ca2+ uptake was measured after stimulation by PAF. Platelet aggregation was studied by recording the change in light transmission with platelet rich plasma (PRP) or washed platelet suspension (WPS).These three Ca2+ -indicators could determine the elevation of [Ca2+ ]cyt that was stimulated by PAF in the presence of extra- cellular Ca2+ (quin2 method: 98.2nM to 289.7nM; fura-2 method: 102.OnM to 351.4nM; aequorin method: 4.1μM to 8.2μM). In the absence of extracellular Ca2+ , however, little elevation of [Ca2+ ]cyt was detected after stimulation by PAF. PAF could evoke the transient Ca2+ uptake.New PAF specific antagonist, ONO-6240 inhibited PAF-induced platelet aggregation at a concentration from lμM dose-dependently, whereas it didn’t inhibit collagen- and thrombin-induced platelet aggregation at a concentration of lOOyM. ONO-6240 inhibited PAF- induced increase in [Ca2+ ]cyt in a dose-dependent manner as deter mined by these Ca2+ -indicators, as well as platelet aggregation.These results suggest the increase in [Ca2+ ]cyt is responsible for platelet aggregation induced by PAF, and the increased Ca2+ is derived from external Ca2+ influx chiefly.

scholarly journals Consumption of plant extract supplement reduces platelet activating factor-induced platelet aggregation and increases platelet activating factor catabolism: a randomised, double-blind and placebo-controlled trial

2019 ◽  
Vol 121 (09) ◽  
pp. 982-991 ◽  
Author(s):  
Lamprini Gavriil ◽  
Maria Detopoulou ◽  
Filio Petsini ◽  
Smaragdi Antonopoulou ◽  
Elizabeth Fragopoulou
Keyword(s):  
Platelet Aggregation ◽  
Healthy Volunteers ◽  
Plant Extracts ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Controlled Trial ◽  
Platelet Activating Factor ◽  
Double Blind ◽  
Metabolism Enzymes ◽  
Baseline Levels

AbstractPlatelet-activating factor (PAF) is a potent mediator of inflammation that plays a crucial role in atherosclerosis. The purpose of this study was to evaluate the effect of a dietary supplement containing mainly plant extracts on PAF actions and metabolism in healthy volunteers. A double-blind, placebo-controlled, 8 weeks’ duration study was performed. Healthy volunteers were randomly allocated into the supplement or the placebo group and fifty-eight of them completed the study. The supplement contained plant extracts (Aloe gel, grape juice, Polygonum cuspidatum) and vitamins. The activities of PAF metabolic enzymes: the two isoforms of acetyl-CoA:lyso-PAF acetyltransferase, cytidine 5’-diphospho-choline:1-alkyl-2-acetyl-sn-glycerol cholinephosphotransferase (PAF-cholinephosphotransferase) and platelet-activating factor–acetylhydrolase (PAF-AH) in leucocytes and lipoprotein associated phospholipase-A2 in plasma were measured along with several markers of endothelial function. Platelet aggregation against PAF, ADP and thrombin receptor activating peptide was measured in human platelet-rich plasma by light transmission aggregometry. No difference was observed on soluble vascular cell adhesion molecule-1, sP-selectin and IL-6 levels at the beginning or during the study period between the two groups. Concerning PAF metabolism enzymes’ activity, no difference was observed at baseline between the groups. PAF-AH activity was only increased in the supplement group at 4 and 8 weeks compared with baseline levels. In addition, supplement consumption led to lower platelet sensitivity against PAF and ADP compared with baseline levels. However, a trial effect was only observed when platelets were stimulated by PAF. In conclusion, supplementation with plant extracts and vitamins ameliorates platelet aggregation primarily against PAF and secondarily against ADP and affects PAF catabolism by enhancing PAF-acetylhydrolase activity in healthy subjects.

Platelet-activating factor and the kidney

1986 ◽  
Vol 251 (1) ◽  
pp. F1-F11 ◽  
Author(s):  
D. Schlondorff ◽  
R. Neuwirth
Keyword(s):  
De Novo ◽  
Mesangial Cells ◽  
Biological Activities ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Initial Step ◽  
Renal Physiology ◽  
Dependent Manner ◽  
Glomerular Mesangial Cells ◽  
Isolated Kidney

Platelet-activating factor (PAF) represents a group of phospholipids with the basic structure of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine. A number of different cells are capable of producing PAF in response to various stimuli. The initial step of PAF formation is activation of phospholipase A2 in a calcium-dependent manner, yielding lyso-PAF. During this step arachidonic acid is also released and can be converted to its respective cyclooxygenase and lipoxygenase products. The lyso-PAF generated is then acetylated in position 2 of the glycerol backbone by a coenzyme A (CoA)-dependent acetyltransferase. An additional pathway may exist whereby PAF is generated de novo from 1-alkyl-2-acetyl-sn-glycerol by phosphocholine transferase. PAF inactivation in cells and blood is by specific acetylhydrolases. PAF exhibits a variety of biological activities including platelet and leukocyte aggregation and activation, increased vascular permeability, respiratory distress, decreased cardiac output, and hypotension. In the kidney PAF can produce decreases in blood flow, glomerular filtration, and fluid and electrolyte excretion. Intrarenal artery injection of PAF may also result in glomerular accumulation of platelets and leukocytes and mild proteinuria. PAF increases prostaglandin formation in the isolated kidney and in cultured glomerular mesangial cells. PAF also causes contraction of mesangial cells. Upon stimulation with calcium ionophore the isolated kidney, isolated glomeruli and medullary cells, and cultured mesangial cells are capable of producing PAF. The potential role for PAF in renal physiology and pathophysiology requires further investigation that may be complicated by 1) the multiple interactions of PAF, prostaglandins, and leukotrienes and 2) the autocoid nature of PAF, which may restrict its action to its site of generation.

scholarly journals A randomised placebo-controlled double-blind multicentre trial comparing antibiotic therapy with placebo in the treatment of uncomplicated acute appendicitis: APPAC III trial study protocol

BMJ Open ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. e023623 ◽  
Author(s):  
Suvi Sippola ◽  
Juha Grönroos ◽  
Ville Sallinen ◽  
Tero Rautio ◽  
Pia Nordström ◽  
...  
Keyword(s):  
Acute Appendicitis ◽  
Antibiotic Therapy ◽  
Ct Scan ◽  
Symptomatic Treatment ◽  
Spontaneous Resolution ◽  
University Hospital ◽  
Controlled Study ◽  
Double Blind ◽  
Uncomplicated Acute Appendicitis

IntroductionRecent studies show that antibiotic therapy is safe and feasible for CT-confirmed uncomplicated acute appendicitis. Spontaneous resolution of acute appendicitis has already been observed over a hundred years ago. In CT-confirmed uncomplicated acute diverticulitis (left-sided appendicitis), studies have shown no benefit from antibiotics compared with symptomatic treatment, but this shift from antibiotics to symptomatic treatment has not yet been widely implemented in clinical practice. Recently, symptomatic treatment of uncomplicated acute appendicitis has been demonstrated in a Korean open-label study. However, a double-blinded placebo-controlled study to illustrate the role of antibiotics and spontaneous resolution of uncomplicated acute appendicitis is still lacking.Methods and analysisThe APPAC III (APPendicitis ACuta III) trial is a multicentre, double-blind, placebo-controlled, superiority randomised study comparing antibiotic therapy with placebo in the treatment CT scan-confirmed uncomplicated acute appendicitis aiming to evaluate the role of antibiotics in the resolution of uncomplicated acute appendicitis. Adult patients (18–60 years) with CT scan-confirmed uncomplicated acute appendicitis (the absence of appendicolith, abscess, perforation and tumour) will be enrolled in five Finnish university hospitals.Primary endpoint is success of the randomised treatment, defined as resolution of acute appendicitis resulting in discharge from the hospital without surgical intervention within 10 days after initiating randomised treatment (treatment efficacy). Secondary endpoints include postintervention complications, recurrent symptoms after treatment up to 1 year, late recurrence of acute appendicitis after 1 year, duration of hospital stay, sick leave, treatment costs and quality of life. A decrease of 15 percentage points in success rate is considered clinically important difference. The superiority of antibiotic treatment compared with placebo will be analysed using Fisher’s one-sided test and CI will be calculated for proportion difference.Ethics and disseminationThis protocol has been approved by the Ethics Committee of Turku University Hospital and the Finnish Medicines Agency (FIMEA). The findings will be disseminated in peer-reviewed academic journals.Trial registration numberNCT03234296; Pre-results.

Abstract 40: Prothrombotic Role of Platelet Tlr2 in Hyperlipidemia

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Sudipta Biswas ◽  
Liang Xin ◽  
Soumya Panigrahi ◽  
Alejandro Zimman ◽  
Valentin Yakubenko ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Platelet Reactivity ◽  
Biological Activities ◽  
Biologically Active ◽  
Dependent Manner ◽  
Prothrombotic State ◽  
Downstream Signaling ◽  
Subsequent Activation ◽  
Biologically Active Derivatives

A prothrombotic state and increased platelet reactivity are common in hyperlipidemia and oxidative stress. Lipid peroxidation, a major consequence of oxidative stress, generates highly reactive products including hydroxy-w-oxoalkenoic acids that modify autologous proteins generating biologically active derivatives. Phosphatidylethanolamine, the second most abundant eukaryotic phospholipid can also be modified by hydroxy-w-oxoalkenoic acids. However, the conditions leading to accumulation of such derivatives in circulation and their biological activities remain poorly understood. We now show that carboxyalkylpyrrole-phosphatidylethanolamine derivatives (CAP-PE) accumulate in plasma of hyperlipidemic ApoE -/- mice. CAP-PE directly bind to TLR2 and induce platelet integrin alpha 2b beta 3 activation and P-selectin expression in TLR2 dependent manner. Platelet activation by CAP-PE includes assembly of TLR2/TLR1 receptor complex, induction of downstream signaling via MyD88/TIRAP, phosphorylation of IRAK4, and subsequent activation of TRAF6. This in turn activates the Src family kinases, Syk and PLC gamma 2 and platelet integrins. By intravital thrombosis studies we have demonstrated that CAP-PE accelerate thrombosis in TLR2 dependent manner. Furthermore, we demonstrate that TLR2 deficient mice are protected from accelerated thrombosis induced by hyperlipidemia. Taken together, our studies demonstrate a cross-talk between innate immunity and integrin activation signaling pathways in platelets and reveal that TLR2 plays a key role in platelet hyperreactivity and prothrombotic state in hyperlipidemia.

The Role Of Calcium In Platelet Microtubule Assembly- Disassembly

1981 ◽  
Author(s):  
M Kikuchi ◽  
Y Ikeda ◽  
M Handa ◽  
S Matsuda ◽  
H Muraki ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Dynamic Equilibrium ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Microtubule Assembly ◽  
Base Line ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Transient Decrease

Microtubules exist in a dynamic equilibrium between polymerized and depolymerized forms in human platelets, playing a major role to maintain the discoid shape of platelets. It has been previously shown that the interaction of aggregating agents with platelets leads to a rapid but transient disassembly of microtubules. ( Steiner and Ikeda, J.Clin. Invest. 63:443,1979 ) In this paper, the role of calcium in the equilibrium between assembled and disassembled microtubules was investigated. The respective pools of soluble and polymerized tubulin were “frozen” by addition of a glycerol-dimethyl sulfoxide-containing medium to platelet rich plasma, preincubated with 2 µM A23187 for various time intervals. The two pools of tubulin were estimated by measuring the colchicine binding activities of total and polymerized tubulin according to the method of Wilson.Resting platelets were found to contain 56.2 ± 2.7 µg tubulin per 109 platelets, of which 56.7 % was in polymerized form. Addition of A23187 to platelet rich plasma produced a transient decrease in the pool of polymerized tubulin within 30 sec., followed by a return to base-line values within 2 min.. TMB-8, a known intracellular calcium antagonist, abolished this transient decrease in polymerized tubulin induced by A23187 in a concentration dependent manner, while indomethacin or acetylsalycylic acid did not.These findings may indicate the important role of intracellular calcium in microtubule assembly-disassembly.

Recent developments in the psychopharmacology of social phobia

1993 ◽  
Vol 5 (4) ◽  
pp. 76-82
Author(s):  
Den J.A. Boer ◽  
I.M. Van Vliet ◽  
H.G.M. Westenberg
Keyword(s):  
Social Anxiety ◽  
Social Phobia ◽  
Research Effort ◽  
Beta Blockers ◽  
Controlled Study ◽  
Social Avoidance ◽  
Double Blind ◽  
Compulsive Disorder ◽  
Serotonergic Drugs

SummaryThe last two decades have witnessed an upsurge in the interest in anxiety disorders. Much research effort has been dedicated to panic disorder and obsessive compulsive disorder. However, it is only very recently that we have begun to understand some of the basic principles about the psychopharmacology of social phobia. Drug classes so far studied include beta-blockers, non-selective and irreversible MAO-inhibitors (MAOI's) and benzodiazepinen. Beta-blockers appear to be of use in specific social phobias, like public speaking. There is considerable evidence suggesting that MAOI's are effective in reducing both social anxiety as well as social avoidance. A disadvantage of the conventional irreversible MAOI's is their risk for hypertensive crises when combined with dietary tyramine.So far only a small number of studies with selective MAOI-A inhibitors such as moclobemide and brofaromine have been conducted in social phobia, and the results indicate that both compounds are effective.Drugs exerting selective and specific actions on certain components of e.g. the serotonergic system can now be studied and it is hoped that the role of serotonin and other neuronal systems in social phobia can be elucidated.In order to gain more information about selective serotonergic drugs the first double blind placebo-controlled study with fluvoxamine in social phobia is here reported. Preliminary results indicate a reduction of social anxiety.Finally the role of peptides in the treatment of social phobia is critically reviewed. The MSH/ACTH analog Org 2766 was investigated in patients suffering from social phobia. No anxiolytic effects of this peptide could be observed.

scholarly journals Short-Term Outcomes of Percutaneous Trephination with a Platelet Rich Plasma Intrameniscal Injection for the Repair of Degenerative Meniscal Lesions. A Prospective, Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Study

2019 ◽  
Vol 20 (4) ◽  
pp. 856 ◽  
Author(s):  
Rafal Kaminski ◽  
Marta Maksymowicz-Wleklik ◽  
Krzysztof Kulinski ◽  
Katarzyna Kozar-Kaminska ◽  
Agnieszka Dabrowska-Thing ◽  
...  
Keyword(s):  
Platelet Rich Plasma ◽  
Meniscal Tear ◽  
Controlled Study ◽  
Control Group ◽  
Double Blind ◽  
Non Union ◽  
Parallel Group ◽  
Significant Difference ◽  
Clinically Significant ◽  
Patient Related Outcome

Meniscal tears are the most common orthopaedic injuries, with chronic lesions comprising up to 56% of cases. In these situations, no benefit with surgical treatment is observed. Thus, the purpose of this study was to investigate the effectiveness and safety of percutaneous intrameniscal platelet rich plasma (PRP) application to complement repair of a chronic meniscal lesion. This single centre, prospective, randomized, double-blind, placebo-controlled study included 72 patients. All subjects underwent meniscal trephination with or without concomitant PRP injection. Meniscal non-union observed in magnetic resonance arthrography or arthroscopy were considered as failures. Patient related outcome measures (PROMs) were assessed. The failure rate was significantly higher in the control group than in the PRP augmented group (70% vs. 48%, P = 0.04). Kaplan-Meyer analysis for arthroscopy-free survival showed significant reduction in the number of performed arthroscopies in the PRP augmented group. A notably higher percentage of patients treated with PRP achieved minimal clinically significant difference in visual analogue scale (VAS) and Knee injury and Osteoarthritis Outcome Score (KOOS) symptom scores. Our trial indicates that percutaneous meniscal trephination augmented with PRP results in a significant improvement in the rate of chronic meniscal tear healing and this procedure decreases the necessity for arthroscopy in the future (8% vs. 28%, P = 0.032).

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