1
|
Henrich A, Claussen CH, Dingemanse J, Krause A. Pharmacokinetic/pharmacodynamic modeling of drug interactions at the P2Y 12 receptor between selatogrel and oral P2Y 12 antagonists. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2021; 10:735-747. [PMID: 33955698 PMCID: PMC8302241 DOI: 10.1002/psp4.12641] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 11/19/2022]
Abstract
Selatogrel is a potent and reversible P2Y12 receptor antagonist developed for subcutaneous self‐administration by patients with suspected acute myocardial infarction. After single‐dose emergency treatment with selatogrel, patients are switched to long‐term treatment with oral P2Y12 receptor antagonists. Selatogrel shows rapid onset and offset of inhibition of platelet aggregation (IPA) to overcome the critical initial time after acute myocardial infarction. Long‐term benefit is provided by oral P2Y12 receptor antagonists such as clopidogrel, prasugrel, and ticagrelor. A population pharmacokinetic (PK)/pharmacodynamic (PD) model based on data from 545 subjects in 4 phase I and 2 phase II studies well described the effect of selatogrel on IPA alone and in combination with clopidogrel, prasugrel, and ticagrelor. The PK of selatogrel were described by a three‐compartment model. The PD model included a receptor‐pool compartment to which all drugs can bind concurrently, reversibly or irreversibly, depending on their mode of action. Furthermore, ticagrelor and its active metabolite can bind to the selatogrel‐receptor complex allosterically, releasing selatogrel from the binding site. The model provided a framework for predicting the effect on IPA of selatogrel followed by reversibly and irreversibly binding oral P2Y12 receptor antagonists for sustained effects. Determining the timepoint for switching from emergency to maintenance treatment is critical to achieve sufficient IPA at all times. Simulations based on the interaction model showed that loading doses of clopidogrel and prasugrel administered 15 h and 4.5 h after selatogrel, respectively, provide sustained IPA with clinically negligible drug interaction. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?
Selatogrel is a potent reversible P2Y12 receptor antagonist developed for subcutaneous self‐administration by patients in case of suspected acute myocardial infarction. Transition to oral P2Y12 receptor antagonists without drug interaction and sufficient inhibition of platelet aggregation must be assured at all times.
WHAT QUESTION DID THIS STUDY ADDRESS?
The pharmacokinetic/pharmacodynamic model semimechanistically describes the effect of selatogrel on platelet inhibition alone and in combination with the oral P2Y12 receptor antagonists clopidogrel, prasugrel, and ticagrelor.
WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?
Model‐based simulations showed that loading doses of clopidogrel and prasugrel can be administered from 15 h and 4.5 h after selatogrel, respectively.
HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?
These results support guiding the clinical transition from selatogrel emergency treatment to oral maintenance therapy in a safe and efficacious way.
Collapse
Affiliation(s)
- Andrea Henrich
- Clinical Pharmacology, Idorsia Pharmaceuticals Ltd, Allschwil, Switzerland
| | - Christian Hove Claussen
- Cognigen Corporation, A Simulation Plus Company, Pharmacometrics Services, Copenhagen, Denmark
| | - Jasper Dingemanse
- Clinical Pharmacology, Idorsia Pharmaceuticals Ltd, Allschwil, Switzerland
| | - Andreas Krause
- Clinical Pharmacology, Idorsia Pharmaceuticals Ltd, Allschwil, Switzerland
| |
Collapse
|
2
|
Icli A, Aksoy F, Nar G, Kaymaz H, Alpay MF, Nar R, Guclu A, Arslan A, Dogan A. Increased Mean Platelet Volume in Familial Hypercholesterolemia. Angiology 2015; 67:146-50. [DOI: 10.1177/0003319715579781] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Familial hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism and increases the risk of premature cardiovascular diseases. In patients with FH, platelet function may be activated; however, the extent of this activation and its etiology are unclear. We aimed to evaluate the mean platelet volume (MPV), a marker of platelet activation, in patients with FH. The study group consisted of 164 patients with FH and 160 control patients. Controls were matched for age, gender, hypertension, and smoking. The MPV was significantly higher in patients with FH than in controls (9.2 ± 0.4 vs 7.9 ± 0.6 fL, respectively; P < .001). Platelet count was significantly lower among patients with FH when compared to control patients (259 ± 51 vs 272 ± 56 × 103/L, respectively; P = .03). In linear regression analysis, MPV was independently associated only with total cholesterol (β = .6, 95% confidence interval: 0.004-0.008, P < .001). We have shown that MPV was increased in patients with FH and that it was independently associated with total cholesterol level.
Collapse
Affiliation(s)
- Atilla Icli
- Department of Cardiology, Ahi Evran University, Kirsehir, Turkey
| | - Fatih Aksoy
- Department of Cardiology, Suleyman Demirel University, Isparta, Turkey
| | - Gökay Nar
- Department of Cardiology, Ahi Evran University, Kirsehir, Turkey
| | - Haci Kaymaz
- Department of Neurosurgery, Ahi Evran University Education and Research Hospital, Kirsehir, Turkey
| | - Mehmet Fatih Alpay
- Department of Cardiovascular Surgery, Ahi Evran University, Kirsehir, Turkey
| | - Rukiye Nar
- Department of Biochemistry, Ahi Evran University, Kirsehir, Turkey
| | - Aydın Guclu
- Department of Nephrology, Ahi Evran University, Kirsehir, Turkey
| | - Akif Arslan
- Department of Cardiology, Suleyman Demirel University, Isparta, Turkey
| | - Abdullah Dogan
- Department of Cardiology, Katip Celebi University, Izmir, Turkey
| |
Collapse
|
3
|
Abdelhalim MAK, Siiddiqi NJ, Alhomida AS, Al-Ayed MS. Effects of feeding periods of high cholesterol and saturated fat diet on blood biochemistry and hydroxyproline fractions in rabbits. Bioinform Biol Insights 2008; 2:95-100. [PMID: 19812768 PMCID: PMC2735948 DOI: 10.4137/bbi.s445] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Hypercholesterolemia and hypertriglyceridemia are considered as important risk factors during the atherosclerotic process. The aim of the present investigation was to study the total cholesterol (TC), low-density lipoprotein cholesterol (LDLC), high density lipoprotein (HDL), triglyceride (TG), platelet levels and hydroxyproline fractions during the pathogenesis of atherosclerosis. For this purpose, twenty five 12-weeks, New Zealand white male rabbits, were purchased, individually caged, and divided into either control group or cholesterol-fed group. The control group (n = 10) was fed 100 g/day of normal diet, ORC-4 (Oriental Yeast Co. Ltd., Tokyo, Japan) for a period of 15 weeks. The cholesterol-fed group (n = 15) was fed a high cholesterol and saturated fat diet of ORC-4 containing 1% cholesterol plus 1% olive oil (100 g/day) for periods of 5 (group 1), 10 (group 2) and 15 (group 3) weeks. Blood sample from each animal was taken at the end of the experimental period for the biochemical analysis. The results of the present study showed that TC, LDLC, TG, HDLC and platelets were significantly (P < 0.01) increased in cholesterol-fed rabbits as compared with control rabbits. The serum hydroxyproline (Hyp) in rabbits belonging to group 1 showed no significant alteration when compared to control group. Group 2 rabbits showed a significant increase of 103% (P < 0.01) and 100% (P < 0.001) in free and protein—bound hydroxyproline fractions respectively when compared to control rabbits. However, there was no significant change in peptide—bound and total serum hydroxyproline levels as compared to the control group (P > 0.05). There was no significant (P > 0.05) decrease of free serum hydroxyproline in group 3 rabbits when compared to control rabbits. On the other hand, group 3 rabbits showed a significant increase in peptide–bound and protein-bound Hyp by 517% (P < 0.05) and 100% (P < 0.01) respectively when compared to control rabbits. However, total serum Hyp in group 3 rabbits showed no significant (P > 0.05) change when compared to control rabbits. These results suggest that feeding rabbits high cholesterol and saturated fat diet for feeding periods of 5, 10 and 15 weeks induced significant change in TC, LDLC, HDL, TG, platelet levels and various Hyp fractions in serum without any significant change in the total Hyp content.
Collapse
Affiliation(s)
- Mohamed A K Abdelhalim
- Department of Physics and Astronomy, Biomedical Science Group, King Saud University, College of Science, Riyadh, Saudi Arabia.
| | | | | | | |
Collapse
|
4
|
Bodin S, Tronchère H, Payrastre B. Lipid rafts are critical membrane domains in blood platelet activation processes. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1610:247-57. [PMID: 12648778 DOI: 10.1016/s0005-2736(03)00022-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Among the various hematopoi;etic cells, platelets are critical for maintaining the integrity of the vascular system. They must be rapidly activated by sequential and coordinated mechanisms in order to efficiently prevent haemorrhage upon vascular injury. Several signal transduction pathways lead to platelet activation in vitro and in vivo, among them, several are initiated via receptors or co-receptors containing immuno-receptor tyrosine-based activation motifs (ITAM) which trigger downstream signalling like the immune receptors in lymphocytes. However, in contrast to immune cells for which the role of lipid rafts in signalling has largely been described, the involvement of laterally segregated membrane microdomains in platelet activation has been investigated only recently. The results obtained until now strongly suggest that early steps of platelet activation via the collagen receptor GpVI or via FcgammaRIIa occur preferentially in these microdomains where specific proteins efficiently organize key downstream signalling pathways. In addition, lipid rafts also contribute to platelet activation via heterotrimeric G-protein-coupled receptors. They are sites where the phosphoinositide (PI) metabolism is highly active, leading to a local generation of lipid second messengers such as phosphatidylinositol 3,4,5-trisphosphate. Here, evidence is accumulating that cholesterol-enriched membrane microdomains are part of a general process that contributes to the efficiency and the coordination of platelet activation mechanisms. Here we will discuss the biochemical and functional characterizations of human platelet rafts and their potential impact in platelet physiopathology.
Collapse
Affiliation(s)
- Stéphane Bodin
- INSERM U563, Centre de Physiophatologie Toulouse Purpan, Département d'Oncogenèse et signalisation dans les cellules hématopoi;étiques, Hôpital Purpan 31059, Toulouse, France
| | | | | |
Collapse
|
5
|
Abstract
PURPOSE OF REVIEW Review the cellular mechanisms and clinical evidence for the use of statins in patients with unstable coronary syndromes. RECENT FINDINGS Clinical trials of statin therapy in acute coronary syndromes demonstrate a rapid improvement in endothelial function, improved perfusion to ischemic myocardium, and an early reduction in cardiovascular events. The early benefit of statin therapy is related to a combination of molecular mechanisms that involve the oxidized LDL receptor (LOX-1), endothelial localized nitric oxide synthase, inflammatory cytokines, interstitial collagenases, and tissue factor expression. In human atheroma, 3 months' use of statin (pravastatin) therapy reduced the content of oxidized LDL, inflammatory cells (macrophage, T cells) infiltrates, and improved plaque stability by increasing the collagen content of the fibrous cap. SUMMARY The antiatherothrombotic effects of statin therapy appear to have important clinical relevance to patients with impaired myocardial perfusion and acute coronary syndrome.
Collapse
Affiliation(s)
- Robert S Rosenson
- Preventive Cardiology Center, Division of Cardiology, Department of Medicine, Northwestern University, The Feinberg School of Medicine, Chicago, IL 60611, USA.
| | | |
Collapse
|
6
|
Abstract
Treatment with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has been accompanied by a reduced risk of cardiovascular events. Rapid onset of clinical benefit and weak correlations between plasma low density lipoprotein-cholesterol levels and coronary lumen change or cardiovascular events indicates that nonlipid mechanisms are involved in this beneficial effects with HMG-CoA reductase inhibitors. Furthermore, more rapid onset of clinical benefit with HMG-CoA reductase inhibitors in patients with acute coronary syndromes or acute myocardial infarction than in those with stable coronary heart disease suggest that HMG-CoA reductase inhibitors facilitate repair of ruptured or ulcerated atherosclerotic plaque, facilitate plaque stabilization and/or reduce thrombus formation on ruptured plaques. Treatment with HMG-CoA reductase inhibitors improved endothelial dysfunction in patients with hypercholesterolemia and this improvement in endothelial function was not correlated with reduction in total serum cholesterol levels. Similarly, reduction in endothelial pre-proendothelin mRNA expression and endothelin synthesis and blood pressure lowering with HMG-CoA reductase inhibitors occurred independent of lipid-lowering. Finally, HMG-CoA reductase inhibitors increased endothelial nitric oxide levels i.e. upregulated endothelial nitric oxide synthetase expression via post-transcriptional mechanisms and prevented its down-regulation by oxidized LDL-C. HMG-CoA reductase inhibitors have been shown to modulate the immune response by inhibiting activation of immune-competent cells such as macrophages, and antigen presentation to macrophages by T cells. Treatment with HMG-CoA reductase inhibitors can reduce expression, production and circulating levels of chemokines (monocyte chemoattractant protein-1) and proinflammatory cytokines [tumor necrosis factoralpha, interleukin (IL)-6 and IL-1beta]. HMG-CoA reductase inhibitors reduced inflammation in human atheroma: significantly fewer macrophages and T cells, less oxidized LDL-C and higher collagen content. In addition, treatment with HMG-CoA reductase inhibitor led to decreased cell death within the atheroma. Treatment with these agents also reduced expression of inducible cellular adhesion molecules, decreased secretion of metalloproteinases by macrophages, reduced vascular smooth muscle cell apoptosis. Lastly, HMG-CoA reductase inhibitors appear to have important effects on the thrombogenesis: reduced expression of tissue factor production and activity; increased production of tissue factor package inhibitor; decreased platelet thrombus formation and improved fibrinolysis as a result of lowered plasminogen activator inhibitor-1 levels. As the pluripotential cardioprotective mechanisms of HMG-CoA reductase inhibitors are further elucidated, it is envisaged that treatment with HMG-CoA reductase inhibitors will be initiated earlier and more frequently in patients with hypercholesterolemia.
Collapse
Affiliation(s)
- R S Rosenson
- Preventive Cardiology Center, Division of Cardiology, Department of Medicine and Preventive Medicine, Northwestern University Medical School, Chicago, Illinois 60611, USA.
| |
Collapse
|
7
|
Abstract
Lipid and nonlipid mechanisms contribute to the beneficial effects of some statins on endothelial function, plaque stability and thrombus formation. The nonlipid effects of statins may contribute to alleviation of tissue ischemia and prevention of acute cardiovascular syndromes. Endothelial dysfunction is reversed by a statin and this beneficial property results, in part, from direct actions on the endothelial vasoactive factors, nitric oxide and endothelin-1. Some statins have been shown to inhibit production of proinflammatory cytokines that regulate many key functions of the vascular wall including monocyte adhesion, chemotaxis, and metalloproteinase secretion. Vascular smooth muscle cell synthetic capacity and viability is inhibited by lipophilic agents, whereas a hydrophilic agent does not interfere with this reparative response. Some statins may impede thrombogenesis by reduced activation of the extrinsic coagulation pathway, inhibition of platelet adhesion and aggregation, and improvement in the rheologic profile.
Collapse
Affiliation(s)
- R S Rosenson
- Preventive Cardiology Center, Rush-Presbyterian-St. Luke's Medical Center, 1725 West Harrison Street, Suite 1159, Chicago, IL 60612, USA
| |
Collapse
|
8
|
Miller GJ. Lipoproteins and the haemostatic system in atherothrombotic disorders. Best Pract Res Clin Haematol 1999; 12:555-75. [PMID: 10856985 DOI: 10.1053/beha.1999.0040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The remarkable extent to which interactions between the plasma lipoproteins, inflammatory factors and the haemostatic system contribute to the response to injury and growth of the plaque in atherosclerosis is being increasingly documented. High plasma concentrations of very-low density (VLDL) and low-density lipoproteins (LDL), together with oxidatively modified LDL and lipoprotein (a), can induce responses in vascular endothelial cells, smooth muscle cells, monocytes/macrophages, platelets, neutrophils and humoral factors that are in a variety of ways both procoagulant and antifibrinolytic. Plasma high-density lipoproteins appear to promote anticoagulant mechanisms. Post-prandial lipaemia is associated with transient changes in factor VII which may be indicative of temporary hypercoagulability. The cellular and humoral effects of LDL and VLDL on the haemostatic system appear to be largely reversible, which may help to explain the prompt improvement in the atherothrombotic state gained by correction of hyperlipidaemia.
Collapse
Affiliation(s)
- G J Miller
- MRC Epidemiology and Medical Care Unit, Wolfson Institute of Preventive Medicine, London, UK
| |
Collapse
|
9
|
Abstract
Atherosclerotic plaque rupture and erosions precipitate thrombus formation and may lead to an acute ischemic syndrome. Lipids and lipoproteins modulate the expression and/or function of thrombotic, fibrinolytic and rheologic factors, and thereby influence hemostasis and potential tissue damage resulting from vascular injury. Triglyceride-enriched lipoproteins are accompanied by elevations in factor VII clotting activity, plasminogen activator inhibitor (PAI-1) and viscosity of blood and plasma. Low density lipoprotein (LDL) promotes platelet activation and tissue factor expression and LDL levels correlate with levels of vitamin K dependent coagulation factors and fibrinogen. Conversely, LDL inhibits tissue factor pathway inhibitor (TFPI) which limits activation of the extrinsic coagulation pathway. High density lipoprotein (HDL) has anti-atherothrombotic properties that result from inhibition of platelet and erythrocyte aggregation, reduced blood viscosity and suppression of tissue factor activity and PAI-1 activity and antigen levels. The effects of lipids and lipoproteins on hemostasis and rheology may have important implications for the clinical sequelae following plaque disruption and erosion.
Collapse
Affiliation(s)
- R S Rosenson
- Department of Medicine, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612, USA.
| | | |
Collapse
|
10
|
Baldassarre D, Mores N, Colli S, Pazzucconi F, Sirtori CR, Tremoli E. Platelet alpha 2-adrenergic receptors in hypercholesterolemia: relationship between binding studies and epinephrine-induced platelet aggregation. Clin Pharmacol Ther 1997; 61:684-91. [PMID: 9209252 DOI: 10.1016/s0009-9236(97)90104-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Platelets isolated from patients with hypercholesterolemia are more sensitive in vitro to various aggregating agents, including epinephrine, than those isolated from normocholesterolemic subjects. Increased platelet reactivity is one mechanism that may explain the enhanced risk of thromboembolism in hypercholesterolemia. This study assessed whether platelet hyperreactivity to epinephrine in hypercholesterolemia is associated with higher alpha 2-adrenergic receptor density or affinity for epinephrine. METHODS Platelet aggregation and binding studies, with use of [3H]yohimbine as ligand, were performed on platelets isolated from 30 patients with type IIa hypercholesterolemia and 23 control subjects. RESULTS Platelet aggregation in response to epinephrine was significantly higher in patients with hypercholesterolemia than in control subjects. A statistically significantly higher alpha 2-adrenergic receptor density was observed in a subgroup of 13 patients with hypercholesterolemia than in 13 sex- and age-matched control subjects (280 +/- 61 and 230 +/- 49 fmol/mg protein respectively; p < 0.03), but no difference was observed in receptor affinity for the ligand. In these subgroups plasma total and levels of low-density lipoprotein (LDL) cholesterol were inversely correlated with platelet aggregation but directly correlated with platelet receptor density. CONCLUSION Platelet alpha 2-adrenergic receptor density is increased in hypercholesterolemia and directly correlates with plasma total and levels of LDL cholesterol, providing at least a partial explanation for the enhanced platelet response to epinephrine that is observed in hypercholesterolemia.
Collapse
Affiliation(s)
- D Baldassarre
- Enrica Grossi Paoletti Center, Institute of Pharmacological Sciences, University of Milan, Italy
| | | | | | | | | | | |
Collapse
|
11
|
Saito K, Sano H, Kawahara J, Yokoyama M. Calcium supplementation attenuates an enhanced platelet function in salt-loaded mildly hypertensive patients. Hypertension 1995; 26:156-63. [PMID: 7607719 DOI: 10.1161/01.hyp.26.1.156] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We designed this study to evaluate the effect of low versus high calcium intake on platelet function in salt-loaded patients with mild hypertension. After a 7-day period of dietary salt restriction, 19 patients were placed on a high salt (300 mmol/d), low calcium (6.25 mmol/d) diet for 7 days; 10 of these patients were given 54 mmol/d of supplementary calcium, and 9 patients were given placebo. At the end of the low and high salt regimens, we evaluated changes in blood pressure, platelet aggregation, and the platelet release reaction measured as plasma beta-thromboglobulin and platelet factor 4 levels. With high salt intake, significant increases in mean blood pressure (P < .02), red blood cell sodium (P < .01), and platelet aggregation induced by 3 mumol/L ADP (P < .01) and by 3.0 mg/L epinephrine (P < .05) were observed in the placebo-treated patients but not in the calcium-supplemented ones. Compared with the placebo-treated patients, calcium-supplemented patients had a smaller weight gain (P < .05) but excreted more sodium and calcium (P < .01) at the end of the high salt regimen. Calcium supplementation resulted in decreases in beta-thromboglobulin (P < .05), platelet factor 4 (P < .01), and plasma and urinary excretions of norepinephrine (P < .02) during the high salt, low calcium regimen. The decrease in plasma norepinephrine correlated positively with the decreases in beta-thromboglobulin (r = .72, P < .02) and platelet factor 4 (r = .85, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- K Saito
- First Department of Internal Medicine, Kobe (Japan) University School of Medicine
| | | | | | | |
Collapse
|
12
|
Miller GJ. Lipoproteins and the haemostatic system in atherothrombotic disorders. BAILLIERE'S CLINICAL HAEMATOLOGY 1994; 7:713-32. [PMID: 7841607 DOI: 10.1016/s0950-3536(05)80105-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The early belief that the haemostatic system has no active role in the formation of the atheromatous plaque is no longer tenable. Rather, the association between hypercholesterolaemia and atherosclerosis appears to arise in part because of various effects of high concentrations of LDL and VLDL particles on the cellular and humoral components of the system, thereby promoting plaque growth and thrombosis. These may be summarized as follows: 1. High concentrations of native LDL have been reported to promote the adhesion of monocytes to the endothelial cell, suggesting that the latter undergoes a form of activation upon such exposure. Oxidized LDL is more potent in this respect, and persistent exposure of endothelium to such particles can eventually lead to cell injury. 2. Activated endothelial cells acquire characteristics on their luminal surface conducive to thrombin generation and fibrin production. Thrombin has several actions on the endothelial cell, monocyte, smooth muscle cell and platelet which in the presence of hypercholesterolaemia will promote the formation of atheroma. 3. Oxidatively modified LDL can activate circulating monocytes, when they also acquire procoagulant properties which favour thrombin production. 4. Platelets show an increased tendency to aggregate when exposed to hypercholesterolaemic plasma. This effect may arise in part because the platelet of the hypercholesterolaemic patient expresses an increased number of fibrinogen binding sites on its surface following activation by agonists such as ADP. These hyperaggregable platelets adhere to activated endothelial cells which express von Willebrand factor on their surface, and to subendothelial proteins exposed in the gaps that open between injured endothelial cells. Platelets exposed to raised LDL levels also show a reduced sensitivity to prostacyclin, an antiaggregatory agent. Oxidatively modified LDL has been reported to stimulate aggregation of platelets in the absence of other agonists such as ADP or thrombin (spontaneous aggregation). 5. Platelet aggregation and fibrin deposition at sites of endothelial injury will create microthrombi which become incorporated into the lesion by organization, thereby increasing the fibrous and cellular content of the atheromatous plaque. 6. Lipolysis of triglyceride-rich lipoproteins at the endothelial cell surface leads to transient activation of the coagulation mechanism with activation of factor VII. Activated factor VII is a potent procoagulant when it forms a complex with tissue factor in the atheromatous lesion. Persistent hypertriglyceridaemia is accompanied by raised concentrations of factor X, factor IX, factor VII and prothrombin. 7. Hypertriglyceridaemia is associated with an increased plasma concentration of PAI-1 and a reduction in plasma fibrinolytic activity.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- G J Miller
- MRC Epidemiology and Medical Care Unit, Wolfson Institute of Preventive Medicine, Medical College of St. Bartholomew's Hospital, London, UK
| |
Collapse
|
13
|
Cadroy Y, Lemozy S, Diquélou A, Ferrières J, Douste-Blazy P, Boneu B, Sakariassen KS. Human type II hyperlipoproteinemia enhances platelet-collagen adhesion in flowing nonanticoagulated blood. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1993; 13:1650-3. [PMID: 8218106 DOI: 10.1161/01.atv.13.11.1650] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We investigated the effects of high plasma lipid levels on platelet adhesion and platelet thrombus formation in nonanticoagulated human blood on collagen fibrils at an arterial wall shear rate of 2600 seconds-1. Nonanticoagulated blood was drawn directly at a flow rate of 10 mL/min for 3 minutes from an antecubital vein of patients with type IIa (n = 5) and type IIb (n = 4) hyperlipoproteinemia over purified human type III collagen fibrils that were positioned on a plastic coverslip in a parallel-plate perfusion chamber. Results were compared with those obtained in healthy individuals with normal lipid plasma levels (n = 9). Blood-collagen interactions were quantified by morphometry as platelet-collagen adhesion, thrombus volume, and fibrin deposition. Platelet-collagen adhesion in the two groups of patients was significantly higher than in healthy individuals (70.7 [61.2 to 82.0] and 70.3 [66.4 to 81.0] in types IIa and IIb patients, respectively, versus 51.2 [44.5 to 68.6] in control subjects; P < .05. All values are percent median [range]). In contrast, the thrombus volume was similar in the three groups (11.3 [8.0 to 13.0], 9.6 [6.4 to 15.3], and 10.2 [6.8 to 16.1] microns3/microns2 [range], respectively). Differences in fibrin deposition were not observed. Thus, it appears that platelet-collagen adhesion is augmented in patients with type IIa and IIb hyperlipoproteinemia, indicating that the process of thrombogenesis is hastened in these patients.
Collapse
Affiliation(s)
- Y Cadroy
- Laboratoire d'Hémostase, Hôpital Purpan, Toulouse, France
| | | | | | | | | | | | | |
Collapse
|
14
|
Gross PL, Rand ML, Barrow DV, Packham MA. Platelet function in Watanabe heritable hyperlipidemic rabbits. Decreased sensitivity to thromboxane A2. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1991; 11:610-6. [PMID: 2029501 DOI: 10.1161/01.atv.11.3.610] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The characteristics of platelets from seven 5-7-month-old homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits (plasma cholesterol, 13.9 +/- 1.7 mM, mean +/- SEM) were compared with those of platelets from normocholesterolemic age/weight- and sex-matched control rabbits (plasma cholesterol, 2.2 +/- 0.3 mM). Whole-blood platelet count and platelet size and protein content were not different in the two groups of rabbits, and the platelets from the WHHL rabbits were not enriched in cholesterol as indicated by identical mean cholesterol:phospholipid molar ratios (C/P). Responses of washed platelets stimulated with various agonists were studied to determine the effects of the genetically determined hypercholesterolemia on the various pathways of platelet aggregation in the absence of plasma components. In platelets from WHHL rabbits compared with controls, aggregation induced by ADP (0.5-5 microM) did not differ; collagen-induced (0.25-1.5 micrograms/ml) responses (aggregation, secretion of carbon-14-labeled serotonin from the amine storage granules of prelabeled platelets, and thromboxane A2 [TxA2] formation) were significantly less extensive; with aspirin-treated platelets, aggregation and secretion of granule contents induced by the TxA2 mimetic U46619 (0.25-1 microM) were significantly less extensive; and thrombin-induced (0.005-0.1 unit/ml) responses of untreated platelets (aggregation, secretion of granule contents, and TxA2 formation) or aspirin-treated platelets (aggregation and secretion of granule contents) did not differ. These observations are in direct contrast with previous studies of platelets from rabbits with diet-induced hypercholesterolemia, in which responses to TxA2 and thrombin were enhanced. Platelets from WHHL rabbits are hyposensitive to aggregation induced by TxA2.
Collapse
Affiliation(s)
- P L Gross
- Department of Biochemistry, University of Toronto, Ontario, Canada
| | | | | | | |
Collapse
|
15
|
Malle E, Sattler W, Prenner E, Leis HJ, Karàdi I, Knipping G, Romics L, Kostner GM. Platelet membrane fluidity in type IIA, type IIB and type IV hyperlipoproteinemia. Atherosclerosis 1991; 87:159-67. [PMID: 1854362 DOI: 10.1016/0021-9150(91)90018-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Fluorescence spectroscopy, a very sensitive index for measuring the biophysical properties of living cell systems, was used to examine the structural order of intact, resting, gel-filtered platelets from hyperlipidemic subjects (n = 48, 25-70 years) and normolipemic subjects (n = 34, 19-68 years). Fluorescence anisotropy (r[s]), which is inversely related to membrane fluidity, was estimated using 3 different fluorescent dyes, DPH, TMA-DPH, and 6-AS, known to label different regions of biological membranes. Increased membrane fluidity was observed in type IIB (n = 24, 36-62 yrs; r[s] = 0.0692 +/- 0.09) and type IV (n = 10, 33-57 yrs; r[s] = 0.058 +/- 0.006) hyperlipidemics in comparison to type IIA (n = 14, 25-70 yrs; r[s] = 0.086 +/- 0.019) and control subjects (n = 24, 28-68 yrs; r[s] = 0.079 +/- 0.012). The temperature dependency of r[s]-DPH values was significantly different (P less than 0.01) in platelets from type IIB and type IV patients compared to type IIA and control subjects of similar age. A significant positive correlation (P less than 0.005) between membrane fluidity and age was found only in healthy control subjects (n = 34, 19-68 yrs). Despite significant (P less than 0.01) differences in plasma lipid concentrations in hyperlipidemic patients and controls, significant ex vivo relations between membrane fluidity and lipoprotein concentrations, free fatty acid distribution, and increased age were found only in healthy control subjects. Plasma levels of thromboxane as well as serum selenium concentrations did not significantly differ between hypercholesterolemic, hypertriglyceridemic, and control subjects.
Collapse
Affiliation(s)
- E Malle
- Institute of Medical Biochemistry, Karl-Franzens University, Graz, Austria
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Schick BP. Effect of diet-induced hypercholesterolemia on proteoglycan metabolism in guinea pig megakaryocytes and platelets. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1991; 11:191-7. [PMID: 1987997 DOI: 10.1161/01.atv.11.1.191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Proteoglycan metabolism was evaluated in megakaryocytes and platelets from guinea pigs fed a 1% cholesterol diet for 3 or 7 weeks. The animals were injected with a single dose of [35S]sulfate at the end of the feeding period, and megakaryocytes and platelets were isolated after 3 hours and then daily for 4 days thereafter. Proteoglycans were extracted from the cells of each animal and analyzed by ion-exchange chromatography, gel filtration, and electrophoresis. The maximal labeling of platelets occurred 2 days after [35S]sulfate injection as compared with 3 days in controls. A proteoglycan that eluted at Kav 0.2 from the Sepharose CL-6B column appeared 1 day after labeling. Additional proteoglycans of Kav 0.15 appeared at subsequent time points. The labeling profile for cholesterol-fed animals was unchanged from 2-4 days, unlike profiles from controls, which had exhibited a gradual increase in mean proteoglycan size. Thus, the progressive change in size of proteoglycans synthesized during normal megakaryocyte maturation was altered. The mean chain length of the proteoglycan-associated glycosaminoglycans from cholesterol-fed animals was increased relative to that of controls. In conjunction with the twofold increase in mean megakaryocyte size induced by cholesterol feeding in guinea pigs, the changes in proteoglycan synthesis suggest a state of stimulated megakaryocytopoiesis.
Collapse
Affiliation(s)
- B P Schick
- Cardeza Foundation for Hematologic Research, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pa
| |
Collapse
|
17
|
Muller S, Ziegler O, Donner M, Drouin P, Stoltz JF. Rheological properties and membrane fluidity of red blood cells and platelets in primary hyperlipoproteinemia. Atherosclerosis 1990; 83:231-7. [PMID: 2242099 DOI: 10.1016/0021-9150(90)90168-i] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Lipid fluidity of the erythrocyte membrane and intact platelets was examined in 32 male patients affected by types IIA, IIB and IV primary hyperlipoproteinemia and 15 control subjects. Lipid fluidity was determined by fluorescence polarization using two probes: DPH and TMA-DPH which are localized in different lipid areas of the cell membrane. Classical haemorheological tests were also performed including plasma viscosity, whole blood viscosity and erythrocyte aggregation. As compared to a control group, plasma viscosity and whole blood viscosity at low shear rate was significantly increased in types IIB and IV, but not in type IIA patients. In contrast, the increase in erythrocyte aggregation was significant in all HLP types. Concerning lipid fluidity, the results recorded with red cells and platelets were not significantly different for type IIA HLP compared to the control group. In contrast, erythrocyte membranes from patients with types IIB and IV HLP had a significantly higher level of fluidity in lipid regions characterized by TMA-DPH. Using DPH as a fluorescent probe, identical results were only noted in type IIB patients. Regarding intact platelets of IIB and IV patients, an increase in lipid fluidity was noted for two fluorescent probes. These findings suggest that HLP associated erythrocyte and platelet fluidity alterations are not related to hypercholesterolemia but to the triglyceride level.
Collapse
Affiliation(s)
- S Muller
- INSERM U. 284, Vandoeuvre-lés-Nancy, France
| | | | | | | | | |
Collapse
|
18
|
Löbel P, Steinhagen-Thiessen E, Schrör K. Cholestyramine treatment of type IIa hypercholesterolaemia normalizes platelet reactivity against prostacyclin. Eur J Clin Invest 1988; 18:256-60. [PMID: 2458263 DOI: 10.1111/j.1365-2362.1988.tb01255.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effect of lowering total plasma and low density lipoprotein (LDL) cholesterol in heterozygous familial hypercholesterolaemia type IIa (FH) on platelet function, thromboxane (TX) formation and platelet sensitivity against iloprost, a stable prostacyclin mimetic, was studied in platelet-rich plasma ex vivo. Seven FH patients were treated with cholestyramine (12 g day 1) for 8-11 months and were compared with eight untreated FH patients and 11 healthy control subjects. In comparison with platelets from healthy controls, platelets from untreated FH patients exhibited a significantly increased aggregation response and TX formation, and a reduced reactivity against inhibition of platelet aggregation by prostacyclin. Treatment with cholestyramine for 8-11 months resulted in a 21% reduction in total serum and LDL-cholesterol. This was not accompanied by any change in platelet hyperreactivity or TX formation. However, cholestyramine treatment normalized the platelet reactivity of FH patients against iloprost, being no more different from healthy controls. It is concluded that reduction in plasma cholesterol by cholestyramine results in normalization of the reduced platelet sensitivity against prostacyclin. This might contribute to beneficial effects of cholestyramine treatment in preventing thromboembolic complications of atherosclerosis.
Collapse
Affiliation(s)
- P Löbel
- Institut für Pharmakologie der Universität Düsseldorf, FRG
| | | | | |
Collapse
|
19
|
Bianciardi G, Toti P, Weber G. The increase of the openings of the surface-connected canalicular system in weakly stimulated platelets is prevented by a carbochromen derivative. A computerized morphometric analysis of freeze-etched human platelet plasma-membrane. PHARMACOLOGICAL RESEARCH COMMUNICATIONS 1987; 19:579-89. [PMID: 3432323 DOI: 10.1016/0031-6989(87)90112-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
When thrombin is added to platelet rich plasma at very low concentrations (0.02 U/ml), platelets undergo an activation process. Under these conditions platelets discharge beta-thromboglobulin, platelet factor 4 and the "platelet derived growth factor". In this paper we present evidence that when human platelets are weakly stimulated with thrombin, the number of openings of the surface connected canalicular system (SCCS) increases. This was observed ultrastructurally by the freeze-etching technique. 8-chlorocarbochromen, an antiaggregating drug, seems to inhibit this increase.
Collapse
Affiliation(s)
- G Bianciardi
- Centro di Ricerche per l'Arteriosclerosi, Universita' di Siena, Italy
| | | | | |
Collapse
|
20
|
Abstract
Enhanced platelet activity in patients with hypercholesterolemia and moderate hypertriglyceridemia can be attributed to increased LDL and VLDL and/or decreased HDL concentrations. In marked hypertriglyceridemia, where there is an accumulation of chylomicrons, platelet function is reduced. Treatment, whether by diet, medication, or plasmapheresis, that will result in a change in lipoprotein pattern is accompanied by a parallel change in platelet responsiveness. Incubation of lipoproteins with isolated platelets results in enhancement of platelet activation by LDL and VLDL and suppression of activity by HDL and chylomicrons. These findings have in vivo confirmation. They are even more pronounced and sometimes altered when the lipoproteins are derived from hyperlipidemic subjects. The effects of the lipoproteins on platelet activity appear to be dependent on lipoprotein composition and on factors such as cholesterol:protein ratio, apo C-III0:apo C-III2 ratio, apo B concentration, and triglyceride:protein ratio. The lipoproteins interact with platelets at specific receptor sites. Rapid change in platelet composition, particularly with regard to cholesterol, phospholipid, and fatty acid content, might ensue, with consequent alterations in membrane fluidity and enzyme activities and either suppression or activation of platelet function. This review has indicated that lipoproteins have a clear influence on platelet function. This interaction could be well of paramount importance in determining atherogenic risk.
Collapse
|
21
|
Butler KD, Butler PA, Shand RA, Ambler J, Wallis RB. Prolongation of platelet survival in hypercholesterolaemic rabbits by CGS 12970 (3-methyl-2-(3-pyridyl)-1 indoleoctanoic acid) and dazoxiben. Thromb Res 1987; 45:751-61. [PMID: 3109067 DOI: 10.1016/0049-3848(87)90085-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In rabbits receiving a normal laboratory diet the platelet half-life was 40.4 +/- 2.5h (mean +/- S.D., n = 35). In animals fed the cholesterol-enriched diet for 12 weeks the platelet half-life was reduced to 31.6 +/- 3.6h (mean +/- S.D., n = 35). Treatment of cholesterol-fed animals with a single daily dose of CGS 12970 (a long acting inhibitor of thromboxane synthase) normalised the platelet half-life. Single daily doses of the relatively shorter acting thromboxane synthase inhibitors (CGS 13080 and dazoxiben) failed to correct the reduced platelet survival. However, twice daily dosing with dazoxiben was effective. The cyclooxygenase inhibitors, aspirin and sulphinpyrazone, failed to correct the reduced platelet survival.
Collapse
|
22
|
Eynard AR, Tremoli E, Caruso D, Magni F, Sirtori CR, Galli G. Platelet formation of 12-hydroxyeicosatetraenoic acid and thromboxane B2 is increased in type IIA hypercholesterolemic subjects. Atherosclerosis 1986; 60:61-6. [PMID: 3085686 DOI: 10.1016/0021-9150(86)90088-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The formation of the major metabolic products of endogenous arachidonic acid (AA) via cyclooxygenase and lipoxygenase pathways in platelets from normal and type IIA hypercholesterolemic subjects was evaluated. 12-Hydroxyeicosatetraenoic acid (12-HETE) and thromboxane B2(TXB2) were determined by selected ion monitoring (SIM) after extraction and purification of collagen stimulated platelet-rich plasma (PRP). The levels of both arachidonic acid metabolites in the non-stimulated PRP of control and type IIA subjects were below the detection limit of the method, rising significantly after collagen stimulation. Both 12-HETE and TXB2 levels in collagen-stimulated PRP samples from the patients were significantly higher than levels in controls (P less than 0.001). In view of the key role of 12-HETE in mediating smooth muscle cell migration and proliferation and in stimulating macrophage activity, these data may provide information for the understanding of the elevated incidence of thrombosis and atheromatous lesion in patients with type IIA hypercholesterolemia.
Collapse
|
23
|
Hamsten A, Svensson J, Walldius G, Szamosi A, de Faire U. Shortened megakaryocyte-platelet regeneration time in young survivors of myocardial infarction. Am Heart J 1985; 110:1154-60. [PMID: 2866703 DOI: 10.1016/0002-8703(85)90005-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Megakaryocyte-platelet regeneration time (MPRT) was determined 6 to 12 months after myocardial infarction in 42 patients below the age of 45 years (mean age +/- SD = 39.4 +/- 4.6, range 23 to 44) and in 11 healthy control subjects by measurement of the reappearance rate of platelet cyclooxygenase activity after oral aspirin. In the young post infarction patients, MPRT was correlated to pertinent metabolic, angiographic, and clinical findings. MPRT for all patients tended to be shorter than in control subjects (t1/2 = 4.53 +/- 1.15 vs 5.22 +/- 0.52; p less than 0.10). Age, present tobacco consumption, serum lipoprotein lipid concentrations, and glucose tolerance, as well as other measured risk factors, did not correlate significantly with MPRT. A marked difference in MPRT, independent of risk factor profile, was present between patients with and without hemodynamically significant stenoses in the coronary angiogram (4.06 +/- 0.92 vs 5.22 +/- 1.07; p less than 0.001). It is suggested that a shortened platelet survival in young post infarction patients is secondary to platelet activation by high-velocity flow and shear forces at the sites of proximal coronary artery stenoses.
Collapse
|
24
|
Weber G, Bianciardi G, Toti P, Massari P, Orlando P. Observations on the effects of some antiaggregating drugs on platelet specific protein discharge after a very weak stimulus. PHARMACOLOGICAL RESEARCH COMMUNICATIONS 1985; 17:129-35. [PMID: 3158006 DOI: 10.1016/0031-6989(85)90059-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Platelet adhesion, aggregation, secretion, and survival have been shown to be changed in atherosclerosis disease and thromboembolic phenomena thus further increasing interest on antiaggregating drugs. In this paper we present some evidence that 8-chlorocarbochromen and carbochromen are significantly effective in preventing the discharge of platelet specific proteins from platelets subjects to a very weak stimulus while acetylsalicylic acid and aminophylline are ineffective in this regard.
Collapse
|
25
|
Tremoli E, Maderna P, Colli S, Morazzoni G, Sirtori M, Sirtori CR. Increased platelet sensitivity and thromboxane B2 formation in type-II hyperlipoproteinaemic patients. Eur J Clin Invest 1984; 14:329-33. [PMID: 6437830 DOI: 10.1111/j.1365-2362.1984.tb01191.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Platelet aggregation induced by collagen, ADP and epinephrine, was monitored in 150 type-II patients (115 type IIA and 35 type IIB) and compared with a reference group of normolipidaemic controls; in addition, malondialydehyde formation and thromboxane B2 were examined in a subsample of the type-IIA patients. Threshold aggregatory concentrations were significantly lower in the whole group of type-II patients for all three aggregating agents; no difference in terms of aggregatory response was detected between platelets from type-IIA and -IIB patients. Only 56% of type-II patients, however, exceeded the 95th percentile of the threshold aggregatory concentrations in controls. The formation of malondialdehyde in platelet-rich plasma stimulated with thrombin and collagen, was significantly higher in platelets from type-IIA patients. The production of thromboxane B2 by platelets, from endogenous arachidonic acid in type-IIA patients, was significantly higher and exceeded the highest level found in controls.
Collapse
|
26
|
Nara Y, Kihara M, Nabika T, Mano M, Horie R, Yamori Y. Dietary effect on platelet aggregation in men with and without a family history of essential hypertension. Hypertension 1984; 6:339-43. [PMID: 6735455 DOI: 10.1161/01.hyp.6.3.339] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Platelet aggregation induced by 5 microM adenosine 5'-diphosphate (ADP) was significantly higher in men with a family history of essential hypertension than in men without such a history when they were fed a low fat-cholesterol diet with low salt. Platelet aggregation activity was remarkably increased in both groups when the diet was changed from low salt into high salt. Platelet aggregation activity was higher in the group with a positive family history of hypertension on the low fat-cholesterol plus high salt diet than in the group without a family history under the same conditions. The activity was slightly increased in both groups when fed a high fat-cholesterol diet with low salt. There was no significant difference in the platelet aggregation between the two groups. The activity was significantly increased in both groups on the high fat-cholesterol diet after the diet was changed from low salt to high salt. Under both the low and high fat-cholesterol diets, the mean blood pressure was significantly elevated in response to excessive salt intake in the group with a family history of essential hypertension, but it was not elevated in the group without such a family history.
Collapse
|
27
|
Sirtori M, Montanari G, Gianfranceschi G, Malacrida MG, Battistin P, Morazzoni G, Tremoli E, Colli S, Maderna P, Sirtori CR. Clofibrate and tiadenol treatment in hyperlipoproteinemias. A comparative trial of drugs affecting lipoprotein catabolism and biosynthesis. Atherosclerosis 1983; 49:149-61. [PMID: 6365105 DOI: 10.1016/0021-9150(83)90192-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Changes in plasma lipoprotein levels and platelet reactivity were evaluated during sequential treatments with clofibrate and tiadenol, two hypolipidemic agents with apparently different mechanisms, in 27 hyperlipoproteinemic patients. The objective of the study was to determine the pattern of plasma lipoprotein variations, induced by a drug mainly affecting lipoprotein catabolism (clofibrate) and by a drug affecting biosynthesis (tiadenol), and to single out-patients specifically responding to either treatment. Both drugs proved significantly active in type IIA and IV hyperlipoproteinemias, not in type IIB. Clofibrate significantly lowered very low density lipoprotein (VLDL) associated cholesterol in all three hyperlipoproteinemia phenotypes, and it also lowered VLDL triglycerides in type IV, while increasing high density lipoprotein (HDL) cholesterol in type IIA patients. Low density lipoprotein (LDL) cholesterol levels were minimally reduced by clofibrate in type IIA (-4%), and increased in types IIB (+ 14.2%) and IV (+ 6.1%) patients. Conversely, tiadenol lowered VLDL cholesterol and triglycerides to a lesser extent, but it did significantly reduce LDL cholesterolemia in type IIA (-17.6%), while increasing HDL cholesterol in type IIB. Statistical evaluation of the results did not permit identification of parameters associated with the response to either drug, although individuals specifically responding to one or the other agent, or to both, were detected in all three phenotypes. The sensitivity to the major platelet aggregating factors, ADP, adrenaline and collagen, was not significantly altered after drug treatments. Evaluation of the hypolipidemic response to agents with different mechanisms may be of help in selecting the best treatment for individual patients.
Collapse
|