scholarly journals Aggregation response of triglyceride hydrolysis products in cyclohexane and triolein

2018 ◽  
Vol 20 (42) ◽  
pp. 27192-27204 ◽  
Author(s):  
Sampsa Vierros ◽  
Monika Österberg ◽  
Maria Sammalkorpi
Keyword(s):  
Head Group ◽  
Aggregation Mechanism ◽  
Triglyceride Hydrolysis ◽  
Solvent Quality ◽  
Hydrolysis Products ◽  
Aggregation Response ◽  
Apolar Solvent

Aggregation mechanism and the existence of cmc depend on apolar solvent quality and surfactant head group polarity.

Effect of Solvent Quality on the Behaviour of Highly Charged Polyelectrolytes

1995 ◽  
Vol 5 (9) ◽  
pp. 1269-1275 ◽  
Author(s):  
W. Essafi ◽  
F. Lafuma ◽  
C. E. Williams
Keyword(s):  
Effect Of Solvent ◽  
Solvent Quality

Increased Response to Arachidonic Acid and U-46619 and Resistance to Inhibitory Prostaglandins in Patients with Chronic Myeloproliferative Disorders

1988 ◽  
Vol 59 (01) ◽  
pp. 073-076 ◽  
Author(s):  
Sergio Cortelazzo ◽  
Monica Galli ◽  
Donatella Castagna ◽  
Piera Viero ◽  
Giovanni de Gaetano ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Myeloproliferative Disorders ◽  
Bone Marrow Stem Cell ◽  
Healthy Controls ◽  
Aggregation Response ◽  
Thrombotic Complications ◽  
Cyclic Endoperoxide ◽  
Marrow Stem Cell

SummaryIn patients with myeloproliferative disorders (MPD) a group of related diseases of the bone marrow stem cell and recurrent haemorrhagic and/or thrombotic complications, the production of aggregating prostaglandins (PGs) may be normal or slightly reduced, while PGI2 production is normal. However, MPD platelet sensitivity to antiaggregatory PGs is still unknown.We studied the potency of PGD2, PGI2 and PGEi as inhibitors of platelet aggregation induced by threshold aggregating concentrations of arachidonic acid and U-46619-analogue of the cyclic endoperoxide PGH2 in 20 patients with MPD in comparison with healthy controls, with the aim of evaluating the sensitivity of MPD platelets to antiaggregatory PGs. In these patients platelet prostanoid metabolism was normal. However, the functional response of platelets to aggregating and antiaggregating prostanoids was shifted towards potentially increased platelet aggregation response. These findings could have a clinical relevance in view of the haemostatic and thrombotic complications so frequent in MPD.

Essential Athrombia

1975 ◽  
Vol 33 (02) ◽  
pp. 278-285 ◽  
Author(s):  
Şeref Inceman ◽  
Yücel Tangün
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Bleeding Tendency ◽  
Clot Retraction ◽  
Platelet Factor ◽  
Prolonged Bleeding Time ◽  
Normal Platelet ◽  
Aggregation Response ◽  
Platelet Disorder ◽  
Fibrinogen Content

SummaryA constitutional platelet function disorder in a twelve-year-old girl characterized by a lifelong bleeding tendency, prolonged bleeding time, normal platelet count, normal clot retraction, normal platelet factor 3 activity and impaired platelet aggregation was reported.Platelet aggregation, studied turbidimetrically, was absent in the presence of usual doses of ADP (1–4 μM), although a small wave of primary aggregation was obtained by very large ADP concentrations (25–50 μM). The platelets were also unresponsive to epinephrine, thrombin and diluted collagen suspensions. But an almost normal aggregation response occurred with strong collagen suspensions. The platelets responded to Ristocetin. Pelease of platelet ADP was found to be normal by collagen and thrombin, but impaired by kaolin. Platelet fibrinogen content was normal.The present case, investigated with recent methods, confirms the existence of a type of primary functional platelet disorder characterized solely by an aggregation defect, described in 1955 and 1962 under the name of “essential athrombia.”

The Mechanism of Platelet Aggregation Induced by HLA-Related Antibodies

1996 ◽  
Vol 76 (05) ◽  
pp. 774-779 ◽  
Author(s):  
John T Brandt ◽  
Carmen J Julius ◽  
Jeanne M Osborne ◽  
Clark L Anderson
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Complement Activation ◽  
Thromboembolic Disease ◽  
Clinical Samples ◽  
Hla Antigen ◽  
Aggregation Response ◽  
Immune Mediated ◽  
Dependent Pathway

SummaryImmune-mediated platelet activation is emerging as an important pathogenic mechanism of thrombosis. In vitro studies have suggested two distinct pathways for immune-mediated platelet activation; one involving clustering of platelet FcyRIIa, the other involving platelet-associated complement activation. HLA-related antibodies have been shown to cause platelet aggregation, but the mechanism has not been clarified. We evaluated the mechanism of platelet aggregation induced by HLA-related antibodies from nine patients. Antibody to platelet FcyRIIa failed to block platelet aggregation with 8/9 samples, indicating that engagement of platelet FcyRIIa is not necessary for the platelet aggregation induced by HLA-related antibodies. In contrast, platelet aggregation was blocked by antibodies to human C8 (5/7) or C9 (7/7). F(ab’)2 fragments of patient IgG failed to induce platelet activation although they bound to HLA antigen on platelets. Intact patient IgG failed to aggregate washed platelets unless aged serum was added. The activating IgG could be adsorbed by incubation with lymphocytes and eluted from the lymphocytes. These results indicate that complement activation is involved in the aggregation response to HLA-related antibodies. This is the first demonstration of complement-mediated platelet aggregation by clinical samples. Five of the patients developed thrombocytopenia in relationship to blood transfusion and two patients developed acute thromboembolic disease, suggesting that these antibodies and the complement-dependent pathway of platelet aggregation may be of clinical significance.

Detection of Carriers in Glanzmann's Thrombasthenia

1983 ◽  
Vol 49 (03) ◽  
pp. 182-186
Author(s):  
G T E Zonneveld ◽  
E F van Leeuwen ◽  
A Sturk ◽  
J W ten Cate
Keyword(s):  
Bleeding Time ◽  
Periodic Acid ◽  
Type I ◽  
Clot Retraction ◽  
Periodic Acid Schiff ◽  
Glanzmann’S Thrombasthenia ◽  
Aggregation Response ◽  
Glanzmann's Thrombasthenia ◽  
Sds Page ◽  
Reduced State

SummaryQuantitative glycoprotein (GP) analysis of whole platelets or platelet membranes was performed by SDS-polyacrylamide gelelectrophoresis (SDS-PAGE) and periodic acid Schiff staining in the families of two unrelated Glanzmann’s thrombasthenia (GT) patients. Each family consisted of two symptom free parents, a symptom free daughter and a GT daughter. All symptom free members had a normal bleeding time, clot retraction and platelet aggregation response to adenosine 5’-diphosphate (ADP), collagen and adrenalin. Platelet Zw* antigen was normally expressed in these subjects. GT patiens, classified as a type I and II subject, showed reduced amounts of GP lib and of GP nia. Analysis of isolated membranes in the non-reduced state, however, showed that the amount of GP Ilia was also reduced in three of the four parents, whereas one parent (of the GT type I patient) and the two unaffected daughters had normal amounts of GP Ilia. Quantitative SDS-PAGE may therefore provide a method for the detection of asymptomatic carriers in GT type I and II.

In Vitro Incorporation and Metabolism of Icosapentaenoic and Docosahexaenoic Acids in Human Platelets - Effect on Aggregation

1986 ◽  
Vol 56 (01) ◽  
pp. 057-062 ◽  
Author(s):  
Martine Croset ◽  
M Lagarde
Keyword(s):  
Arachidonic Acid ◽  
Fatty Acid ◽  
Platelet Aggregation ◽  
Fatty Acid Distribution ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
Aggregation Response ◽  
Docosahexaenoic Acids ◽  
Membrane Level

SummaryWashed human platelets were pre-loaded with icosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or EPA + DHA and tested for their aggregation response in comparison with control platelets. In fatty acid-rich platelets, an inhibition of the aggregation could be observed when induced by thrombin, collagen or U-46619. The strongest inhibition was observed with DHA-rich platelets and it was reduced when DHA was incorporated in the presence of EPA.Study of fatty acid distribution in cell lipids after loading showed that around 90% of EPA or DHA taken up was acylated into phospholipids and a very small amount (less than 2%) remained in their free and hydroxylated forms. DHA was more efficiently acylated into phosphatidylethanolamine (PE) than into phosphatidylinositol (PI) in contrast to what observed with EPA, and both acids were preferentially incorporated into phosphatidylcholine (PC). EPA inhibited total incorporation of DHA and increased its relative acylation into PE at the expense of PC. In contrast, DHA did not affect the acylation of EPA. Upon stimulation with, thrombin, EPA was liberated from phospholipids and oxygenated (as judged by the formation of its monohydroxy derivative) whereas DHA was much less metabolized, although consistently transferred into PE.It is concluded that EPA and DHA might affect platelet aggregation via different mechanisms when pre-loaded in phospholipids. Whereas EPA is known to alter thromboxane A2 metabolism from endogenous arachidonic acid, by competing with it, DHA might act directly at the membrane level for inhibiting aggregation.

Platelet Aggregation, β-Thromboglobulin and Platelet Factor 4 in Diabetes Mellitus and in Patients with Vasculopathy

1984 ◽  
Vol 52 (03) ◽  
pp. 236-239 ◽  
Author(s):  
J Fritschi ◽  
M Christe ◽  
B Lämmle ◽  
G A Marbet ◽  
W Berger ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Platelet Aggregation ◽  
Discriminant Analysis ◽  
Plasma Levels ◽  
Platelet Activating Factor ◽  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Aggregation Response ◽  
The Difference

SummaryWe have studied 155 subjects, 48 normals, 36 diabetics without complications, 44 with complications and 27 patients with macroangiopathy. β-Thromboglobulin (β-TG) and platelet factor 4 (PF4) are elevated in the patients groups. There is no correlation between the plasma levels of β-TG and the stages of either retinopathy or macroangiopathy or nephropathy. The difference is more marked between normals and diabetics with neuropathy (p = 0.026). The aggregation response to ADP and platelet activating factor (PAF) is enhanced at lower stimulator concentration. Using the β-TG, PF4 and aggregation values the discriminant analysis allows a distinction of several subgroups especially with nephropathy and neuropathy (Table 6).

Mechanisms of Drug Solubilization by Polar Lipids in Biorelevant Media

2020 ◽  
Author(s):  
Vladimir Katev ◽  
Zahari Vinarov ◽  
Slavka S. Tcholakova
Keyword(s):  
Chain Length ◽  
Acyl Chain ◽  
Polar Lipids ◽  
Superior Performance ◽  
Head Group ◽  
Formulation Development ◽  
Biorelevant Media ◽  
Drug Solubilization ◽  
Colloidal Aggregates ◽  
Class 1

Despite the widespread use of lipid excipients in both academic research and oral formulation development, rational selection guidelines are still missing. In the current study, we aimed to establish a link between the molecular structure of commonly used polar lipids and drug solubilization in biorelevant media. We studied the effect of 26 polar lipids of the fatty acid, phospholipid or monoglyceride type on the solubilization of fenofibrate in a two-stage <i>in vitro</i> GI tract model. The main trends were checked also with progesterone and danazol.<br>Based on their fenofibrate solubilization efficiency, the polar lipids can be grouped in 3 main classes. Class 1 substances (n = 5) provide biggest enhancement of drug solubilization (>10-fold) and are composed only by unsaturated compounds. Class 2 materials (n = 10) have an intermediate effect (3-10 fold increase) and are composed primarily (80 %) of saturated compounds. Class 3 materials (n = 11) have very low or no effect on drug solubilization and are entirely composed of saturated compounds.<br>The observed behaviour of the polar lipids was rationalized by using two classical physicochemical parameters: the acyl chain phase transition temperature (<i>T</i><sub>m</sub>) and the critical micellar concentration (CMC). Hence, the superior performance of class 1 polar lipids was explained by the double bonds in their acyl chains, which: (1) significantly decrease <i>T</i><sub>m</sub>, allowing these C18 lipids to form colloidal aggregates and (2) prevent tight packing of the molecules in the aggregates, resulting in bigger volume available for drug solubilization. Long-chain (C18) saturated polar lipids had no significant effect on drug solubilization because their <i>T</i><sub>m</sub> was much higher than the temperature of the experiment (<i>T</i> = 37 C) and, therefore, their association in colloidal aggregates was limited. On the other end of the spectrum, the short chain octanoic acid manifested a high CMC (50 mM), which had to be exceeded in order to enhance drug solubilization. When these two parameters were satisfied (C > CMC, <i>T</i><sub>m</sub> < <i>T</i><sub>exp</sub>), the increase of the polar lipid chain length increased the drug solubilization capacity (similarly to classical surfactants), due to the decreased CMC and bigger volume available for solubilization.<br>The hydrophilic head group also has a dramatic impact on the drug solubilization enhancement, with polar lipids performance decreasing in the order: choline phospholipids > monoglycerides > fatty acids.<br>As both the acyl chain length and the head group type are structural features of the polar lipids, and not of the solubilized drugs, the impact of <i>T</i><sub>m</sub> and CMC on solubilization by polar lipids should hold true for a wide variety of hydrophobic molecules. The obtained mechanistic insights can guide rational drug formulation development and thus support modern drug discovery pipelines.<br>

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