Haemostatic Platelet Plug Formation in the Isolated Rabbit Mesenteric Preparation - An Analysis of Red Blood Cell Participation

1980 ◽  
Vol 44 (01) ◽  
pp. 006-008 ◽  
Author(s):  
D Bergqvist ◽  
K-E Arfors
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
In Vitro Test ◽  
Pharmacological Agents ◽  
Vitro Test ◽  
Releasing Effect ◽  
Plug Formation

SummaryIn a model using an isolated rabbit mesenteric preparation microvessels were transected and the time until haemostatic plugs formed was registered. Perfusion of platelet rich plasma gave no haemostasis whereas whole blood did. Addition of chlorpromazine or adenosine to the whole blood significantly prolonged the time for haemostasis, and addition of ADP to the platelet rich plasma significantly shortened it. It is concluded that red cells are necessary for a normal haemostasis in this model, probably by a combination of a haemodynamic and ADP releasing effect.The fundamental role of platelets in haemostatic plug formation is unquestionable but there are still problems concerning the stimulus for this process to start. Three platelet aggregating substances have been discussed – thrombin, adenosine diphosphate (ADP) and collagen. Evidence speaking in favour of thrombin is, however, very minimal, and the discussion has to be focused on collagen and ADP. In an in vitro system using polyethylene tubings we have shown that "haemostasis" can be obtained without the presence of collagen but against these results can be argued that it is only another in vitro test for platelet aggregation (1).To be able to induce haemostasis in this model, however, the presence of red blood cells is necessary. To further study this problem we have developed a model where haemostatic plug formation can be studied in the isolated rabbit mesentery and we have briefly reported on this (2).Thus, it is possible to perfuse the vessels with whole blood as well as with platelet rich plasma (PRP) and different pharmacological agents of importance.

IN VITRO DEMONSTRATION OF "HEPARIN REBOUND"

1987 ◽  
Author(s):  
C Taylor ◽  
R F Baugh
Keyword(s):  
Whole Blood ◽  
Cardiovascular Surgery ◽  
Anticoagulant Activity ◽  
Blood Levels ◽  
In Vitro Test ◽  
Neutralizing Activity ◽  
Vitro Test ◽  
The Stability

"Heparin rebound", the in vivo appearance of measurable heparin anticoagulant activity following theapparent neutralization of heparin by protamine, hasbeen a problem sporadically associated with the use of heparin in cardiovascular surgery. A number of mechanisms have been proposed to explain rebound, and to some extent each may contribute to the phenomena. As yet no reliable, predictable method has been demonstrated for measuring, reproducing or quantifying "heparin rebound".We have demonstrated and measured the appearance of heparin anticoagulant activity following neutralization with protamine in citrated whole blood. The reappearance of heparin anticoagulant activity was associated with a rapid loss of protamine. The loss of protamine followed 1st order enzyme kinetics, and was indicative of the action of an enzyme. The anticoagulant activity which eappeared could be titrated againwith protamine. The loss of protamine neutralizing activity, in whole blood, could be followed by titration with heparin using a recalcified activated clotting time. The rate of loss varied with both individual blood donors and with the type and source of protamine. The rate of loss of protamine was great enough to influence in. vivo heparin/protamine neutralization ratios, i.e. at 4 units of heparin/ml, 1 unit/ml anticoagulant activity was routinely recovered within 30 minutes following initial neutralization. The indications for cardiovascular surgery are:1)the in vivo neutralization ratio should be adjusted to account for loss of protamine activity, 2) the higherthe blood levels of heparin used during surgery, themore significant the potential for heparin rebound, and 3) protamines may be evaluated in an in vitro test which measures the stability of protamine neutralizing activity in whole blood.

Mechanism of platelet plug formation and role of adenosine diphosphate

1964 ◽  
Vol 206 (6) ◽  
pp. 1267-1274 ◽  
Author(s):  
Theodore H. Spaet ◽  
Marjorie B. Zucker
Keyword(s):  
Connective Tissue ◽  
Divalent Cation ◽  
Platelet Rich Plasma ◽  
Adenine Nucleotides ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Suitable Model ◽  
Plug Formation ◽  
Rat Platelets

Traumatized rat omentum was used to demonstrate the development of "platelet plugs" following agitation in platelet-rich plasma. In the absence of divalent cation there was only platelet adhesion to connective tissue fibers; in the presence of divalent cation masses of platelets formed (cohesion) even in plasma adequately anticoagulated with heparin. Exposure of these platelet masses to thrombin produced greater compactness and stability. Human and rat platelets behaved alike with the traumatized rat omentum; platelets from two patients with von Willebrand's disease gave normal reactions whereas platelets from a patient with thrombasthenia showed adhesion only. Exposure of human platelets to washed connective-tissue fragments or to thrombin elicited clumping accompanied by release of serotonin and of adenine nucleotides (AN) of which about one-third was adenosine diphosphate. Intermediate concentrations of connective tissue and thrombin also caused clumping but no liberation of AN or serotonin. ADP caused intense clumping but failed to liberate serotonin or additional ADP. It is suggested that cohesion reaction is mediated by release of ADP. The traumatized omentum appears to be a suitable model for studying the hemostatic process.

scholarly journals Role of the Encapsulation in Bioavailability of Phenolic Compounds

Antioxidants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 923
Author(s):  
Josipa Grgić ◽  
Gordana Šelo ◽  
Mirela Planinić ◽  
Marina Tišma ◽  
Ana Bucić-Kojić
Keyword(s):  
Phenolic Compounds ◽  
Targeted Delivery ◽  
In Vitro Test ◽  
Positive Health ◽  
Coating Materials ◽  
Vitro Test ◽  
Antitumor Properties ◽  
Materials Used

Plant-derived phenolic compounds have multiple positive health effects for humans attributed to their antioxidative, anti-inflammatory, and antitumor properties, etc. These effects strongly depend on their bioavailability in the organism. Bioaccessibility, and consequently bioavailability of phenolic compounds significantly depend on the structure and form in which they are introduced into the organism, e.g., through a complex food matrix or as purified isolates. Furthermore, phenolic compounds interact with other macromolecules (proteins, lipids, dietary fibers, polysaccharides) in food or during digestion, which significantly influences their bioaccessibility in the organism, but due to the complexity of the mechanisms through which phenolic compounds act in the organism this area has still not been examined sufficiently. Simulated gastrointestinal digestion is one of the commonly used in vitro test for the assessment of phenolic compounds bioaccessibility. Encapsulation is a method that can positively affect bioaccessibility and bioavailability as it ensures the coating of the active component and its targeted delivery to a specific part of the digestive tract and controlled release. This comprehensive review aims to present the role of encapsulation in bioavailability of phenolic compounds as well as recent advances in coating materials used in encapsulation processes. The review is based on 258 recent literature references.

Leukocytes Can Enhance Platelet-mediated Aggregation and Thromboxane Release via  Interaction of P-selectin Glycoprotein Ligand 1 with P-selectin

2001 ◽  
Vol 94 (1) ◽  
pp. 145-151 ◽  
Author(s):  
Nauder Faraday ◽  
Robert B. Scharpf ◽  
Jeffrey M. Dodd-o ◽  
Elizabeth A. Martinez ◽  
Brian A. Rosenfeld ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Adenosine Triphosphate ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Live Cells ◽  
Vitro Analysis ◽  
Blocking Antibodies ◽  
Induced Aggregation

Background Platelet--leukocyte conjugates have been observed in patients with unstable coronary syndromes and after cardiopulmonary bypass. In vitro, the binding of platelet P-selectin to leukocyte P-selectin glycoprotein ligand-1 (PSGL1) mediates conjugate formation; however, the hemostatic implications of these cell--cell interactions are unknown. The aims of this study were to determine the ability of leukocytes to modulate platelet agonist--induced aggregation and secretion in the blood milieu, and to investigate the role of P-selectin and PSGL-1 in mediating these responses. Methods Blood was drawn from healthy volunteers for in vitro analysis of platelet agonist--induced aggregation, secretion (adenosine triphosphate, beta-thromboglobulin, and thromboxane), and platelet-leukocyte conjugate formation. Experiments were performed on live cells in whole blood or plasma to simulate physiologic conditions. Whole-blood impedance and optical aggregometry, flow cytometry, and enzyme-linked immunosorbent assays were performed in the presence and absence of blocking antibodies to P-selectin and PSGL1. The platelet-specific agonists, thrombin receptor activating peptide and adenosine diphosphate, were used to elicit platelet activation responses. Results Inhibition of platelet--leukocyte adherence by P- selectin and PSGL1 antibodies decreased agonist--induced aggregation in whole blood. The presence of leukocytes in platelet-rich plasma increased aggregation, and this increase was attenuated by P-selectin blocking antibodies. Data from flow cytometry confirmed that platelet-leukocyte conjugate formation contributed to aggregation responses. Blocking antibodies reduced platelet agonist--induced thromboxane release but had no impact on adenosine triphosphate and beta-thomboglobulin secretion. Conclusions Leukocytes can enhance platelet agonist--induced aggregation and thromboxane release in whole blood and platelet-rich plasma under shear conditions in vitro. Interaction of platelet P-selectin with leukocyte PSGL1 contributes substantially to these effects.

In Vitro and In Vivo Evaluation of Amino Acid-Functionalized Cellulose Beads for Whole Blood Hemoperfusion

2005 ◽  
Vol 288-289 ◽  
pp. 393-396 ◽  
Author(s):  
Yong Jian Wang ◽  
Yao Ting Yu
Keyword(s):  
Rheumatoid Arthritis ◽  
Amino Acid ◽  
Whole Blood ◽  
Blood Perfusion ◽  
In Vitro Test ◽  
Rheumatoid Factors ◽  
In Vivo Evaluation ◽  
Vitro Test

Phenylalanine linked to cellulose beads was designed as an adsorbent in whole blood hemoperfusion for the therapy of rheumatoid arthritis. In whole blood perfusion tests, the adsorbent adsorbed rheumatoid factors directly from whole blood. In vitro test showed that the adsorbent had good biocompability properties. No acute systemic toxicity and dermal irritancy with extremely low skin sensitizing activity were observed. In vivo animal test with satisfactory results was perfumed with rabbits. Experimental results show that the adsorbent holds promise as a highly effective and safe hemoadsorbent in clinical therapy for rheumatoid arthritis patients by hemoperfusion.

The role of seed infection in the spread of blackleg of rape in Western Australia

1977 ◽  
Vol 17 (89) ◽  
pp. 1040 ◽  
Author(s):  
PMcR Wood ◽  
MJ Barbetti
Keyword(s):  
Western Australia ◽  
Leptosphaeria Maculans ◽  
Field Conditions ◽  
In Vitro Test ◽  
Seed Infection ◽  
Infected Seed ◽  
Vitro Test

A survey of rapeseed crops in Western Australia for blackleg (Leptosphaeria maculans (Desm.) Ces and de Not) infection was conducted in November 1972. No correlation between levels of pod infection in November and seed infection at maturity was established. An in vitro test showed that 67 per cent of L. maculans infected seeds gave rise to seedlings with one or both cotyledons infected. Under field conditions in 1974, a plot grown from 5.9 per cent infected seed resulted in 19.0 per cent of plants developing blackleg crown cankers, whereas a plot containing 0.08 per cent infected seed gave 1.1 per cent of plants infected. The following year at a different location, a sample assessed at 0.5 per cent infection produced only 0.06 per cent of plants with crown cankers, and, 0.08 per cent infected seed yielded 0.08 per cent infected plants.

Effect of Dipyridamole on Spontaneous Platelet Aggregation in Whole Blood Decreases with the Time After Venepuncture: Evidence for the Role of ADP

1987 ◽  
Vol 58 (02) ◽  
pp. 744-748 ◽  
Author(s):  
A R Saniabadi ◽  
G D O Lowe ◽  
J C Barbenel ◽  
C D Forbes
Keyword(s):  
Platelet Aggregation ◽  
Correlation Coefficient ◽  
Whole Blood ◽  
Blood Platelet ◽  
Inhibitory Effect ◽  
Time Interval ◽  
Adp Receptor ◽  
Spontaneous Platelet Aggregation

SummarySpontaneous platelet aggregation (SPA) was studied in human whole blood at 3, 5, 10, 20, 30, 40 and 60 minutes after venepuncture. Using a whole blood platelet counter, SPA was quantified by measuring the fall in single platelet count upon rollermixing aliquots of citrated blood at 37° C. The extent of SPA increased with the time after venepuncture, with a correlation coefficient of 0.819. The inhibitory effect of dipyridamole (Dipy) on SPA was studied: (a) 10 μM at each time interval; (b) 0.5-100 μM at 3 and 30 minutes and (c) 15 μM in combination with 100 μM adenosine, 8 μM 2-chloroadenosine (2ClAd, an ADP receptor blocker) and 50 μM aspirin. There was a rapid decrease in the inhibitory effect of Dipy with the time after venepuncture; the correlation coefficient was -0.533. At all the concentrations studied, Dipy was more effective at 3 minutes than at 30 minutes after venepuncture. A combination of Dipy with adenosine, 2ClAd or aspirin was a more effective inhibitor of SPA than either drug alone. However, when 15 μM Dipy and 10 μM Ad were added together, the inhibitory effect of Dipy was not increased significantly, suggesting that Dipy inhibits platelet aggregation independent of Ad. The increase in SPA with the time after venepuncture was abolished when blood was taken directly into the anticoagulant containing 5 μM 2ClAd. It is suggested that ADP released from the red blood cells is responsible for the increased platelet aggregability with the time after venepuncture and makes a serious contribution to the artifacts of in vitro platelet function studies.

Platelet Aggregation in Whole Blood: The Role of Thromboxane A2 and Adenosine Diphosphate

1985 ◽  
Vol 54 (03) ◽  
pp. 612-616 ◽  
Author(s):  
A J Carter ◽  
S Heptinstall
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Adenosine Diphosphate ◽  
Blood Platelet ◽  
Thromboxane B2 ◽  
Lipoxygenase Inhibitor ◽  
Thromboxane Synthase Inhibitor ◽  
Synthase Inhibitor

SummaryThe platelet aggregation that occurred in whole blood in response to several aggregating agents (collagen, arachidonic acid, adenosine diphosphate, adrenaline and thrombin) was measured using an Ultra-Flo 100 Whole Blood Platelet Counter. The amounts of thromboxane B2 produced were measured by radioimmunoassay. The effects of various inhibitors of thromboxane synthesis and the effects of apyrase, an enzyme that destroys adenosine diphosphate, were determined.Platelet aggregation was always accompanied by the production of thromboxane B2, and the amounts produced depended on the nature and concentration of the aggregating agent used. The various inhibitors of thromboxane synthesis - aspirin and flurbiprofen (cyclo-oxygenase inhibitors), BW755C (a cyclo-oxygenase and lipoxygenase inhibitor) and dazoxiben (a selective thromboxane synthase inhibitor) - did not markedly inhibit aggregation. Results obtained using apyrase showed that adenosine diphosphate contributed to the aggregation process, and that its role must be acknowledged when devising means of inhibiting platelet aggregation in vivo.

Early Platelet-Collagen Interactions in Whole Blood and Their Modifications by Aspirin and Dipyridamole Evaluated by a New Method (Basic Wave)

1985 ◽  
Vol 54 (04) ◽  
pp. 799-803 ◽  
Author(s):  
José Luís Pérez-Requejo ◽  
Justo Aznar ◽  
M Teresa Santos ◽  
Juana Vallés
Keyword(s):  
Whole Blood ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
White Blood Cells ◽  
Reversible Aggregation ◽  
Inhibitory Compounds ◽  
Rapid Generation ◽  
Stimulation Of ◽  
Collagen Stimulation

SummaryIt is shown that the supernatant of unstirred whole blood at 37° C, stimulated by 1 μg/ml of collagen for 10 sec, produces a rapid generation of pro and antiaggregatory compounds with a final proaggregatory activity which can be detected for more than 60 min on a platelet rich plasma (PRP) by turbidometric aggregometry. A reversible aggregation wave that we have called BASIC wave (for Blood Aggregation Stimulatory and Inhibitory Compounds) is recorded. The collagen stimulation of unstirred PRP produces a similar but smaller BASIC wave. BASIC’s intensity increases if erythrocytes are added to PRP but decreases if white blood cells are added instead. Aspirin abolishes “ex vivo” the ability of whole blood and PRP to generate BASIC waves and dipyridamole “in vitro” significantly reduces BASIC’s intensity in whole blood in every tested sample, but shows little effect in PRP.

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