scholarly journals The Induction of Platelet Aggregates in Healthy Subjects by Venousocclusion

1977 ◽  
Author(s):  
D.A. F. Chamone ◽  
J. Vermylen
Keyword(s):  
Healthy Subjects ◽  
Light Transmission ◽  
Diastolic Pressure ◽  
Platelet Rich Plasma ◽  
In Vivo Evaluation ◽  
Modified Method ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates ◽  
Set Up

Circulating platelet aggregates have been observed in various clinical conditions (Wu and Hoak, Lancet, 1974, ii, 924). Using a slightly modified method, we have found that platelet aggregates can be induced in vivo in healthy subjects.Nine volunteers (7 males, 2 females, age 23-38 years) were studied. Blood was drawn from an antecubital vein of one arm immediately before and of the other arm after twenty minutes of occlusion midway between systolic and diastolic pressure. The ratio of the platelet count in platelet-rich plasma (PRP) obtained from blood collected on forma lin-EDTA to that from blood collected on EDTA only was 0.934 + 0.028 (mean ± S.E .) before and 0.768 ± 0.033 after occlusion (p < 0.001 ). Spontaneous aggregation in PRP, measured as percent increase in light transmission during 10 minutes of stirring in the a gg re gome ter, was 4 .20 ± 1.17 before and 3 .80 + I .69 after occlusion (p > 0 .1).This system may help elucidate some of the mechanisms involved in the generation of circulating platelet aggregates. It may also constitute a simple set-up for the in vivo evaluation of drugs affecting platelet function.

scholarly journals Do patients with thromboembolic disease have circulating platelet aggregates?

Blood ◽  
1984 ◽  
Vol 64 (1) ◽  
pp. 205-209 ◽  
Author(s):  
FH Kohanna ◽  
MH Smith ◽  
EW Salzman
Keyword(s):  
Platelet Rich Plasma ◽  
Venous Blood ◽  
Adenosine Diphosphate ◽  
Normal Subjects ◽  
Thromboembolic Disease ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates ◽  
Lower Ratio

Reports of circulating platelet aggregates (ie, microemboli) in thromboembolism and other vascular disorders are based on a method (Wu and Hoak , 1974) in which venous blood is collected via scalp vein needle and tubing into either formaldehyde, which fixes aggregates, or EDTA, which disperses them. The ratio of platelet counts in platelet- rich plasma (PRP) from the two blood samples after centrifugation is interpreted as a measure of platelet aggregates in the circulation in vivo. We compared this standard Wu and Hoak technique with a modified one, in which blood was drawn directly into a syringe, and with a third method that avoided centrifugation by counting single platelets in whole blood. Both modified techniques could detect aggregates generated in vitro with adenosine diphosphate (ADP). In 12 normal subjects, the three methods were equivalent, but in 37 patients with thromboembolic disorders, the standard Wu and Hoak method gave a lower ratio than the other methods. Similar results were found in a subset of eight patients with myocardial infarction. Heparin treatment of patients did not influence the results. The data suggest that formation of platelet aggregates occurred during venipuncture. Platelets may be hyperactive in patients with thromboembolic disease and may form aggregates in vitro during collection, but the concept of chronic microembolism in such patients should be reassessed.

scholarly journals Do patients with thromboembolic disease have circulating platelet aggregates?

Blood ◽  
1984 ◽  
Vol 64 (1) ◽  
pp. 205-209 ◽  
Author(s):  
FH Kohanna ◽  
MH Smith ◽  
EW Salzman
Keyword(s):  
Platelet Rich Plasma ◽  
Venous Blood ◽  
Adenosine Diphosphate ◽  
Normal Subjects ◽  
Thromboembolic Disease ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates ◽  
Lower Ratio

Abstract Reports of circulating platelet aggregates (ie, microemboli) in thromboembolism and other vascular disorders are based on a method (Wu and Hoak , 1974) in which venous blood is collected via scalp vein needle and tubing into either formaldehyde, which fixes aggregates, or EDTA, which disperses them. The ratio of platelet counts in platelet- rich plasma (PRP) from the two blood samples after centrifugation is interpreted as a measure of platelet aggregates in the circulation in vivo. We compared this standard Wu and Hoak technique with a modified one, in which blood was drawn directly into a syringe, and with a third method that avoided centrifugation by counting single platelets in whole blood. Both modified techniques could detect aggregates generated in vitro with adenosine diphosphate (ADP). In 12 normal subjects, the three methods were equivalent, but in 37 patients with thromboembolic disorders, the standard Wu and Hoak method gave a lower ratio than the other methods. Similar results were found in a subset of eight patients with myocardial infarction. Heparin treatment of patients did not influence the results. The data suggest that formation of platelet aggregates occurred during venipuncture. Platelets may be hyperactive in patients with thromboembolic disease and may form aggregates in vitro during collection, but the concept of chronic microembolism in such patients should be reassessed.

A Modification of the Wu and Hoak Method for the Determination of Platelet Aggregates and Platelet Adhesion

1985 ◽  
Vol 53 (03) ◽  
pp. 381-385 ◽  
Author(s):  
Sudhir K Bowry ◽  
Colin R M Prentice ◽  
J M Courtney
Keyword(s):  
Platelet Adhesion ◽  
Platelet Rich Plasma ◽  
Blood Collection ◽  
Buffer System ◽  
Modified Method ◽  
Healthy Donors ◽  
Platelet Aggregate ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates

SummaryThe Wu and Hoak method for determining circulating platelet aggregates has poor reproducibility; problems have been reported with the composition of the buffer systems, haemolysis, the effects of blood collection technique and a divergence of the platelet aggregate ratio in blood for healthy donors from the theoretical value of 1. Our investigations suggest that the original technique is highly operator-dependent, especially the collection of blood and the method of counting platelets after centrifugation. We describe an improved modification of the Wu and Hoak technique; a new buffer system has been developed and the proportion of blood in the buffered EDTA and buffered EDTA- formalin solutions has been altered to obtain platelet rich plasma. The platelet aggregate ratio (PAR) by this modified method for healthy donors in two different studies was 0.97 ± 0.02 and 0.98 ± 0.01 respectively. Finally, the principle of Wu and Hoak was used to measure accurately platelet adhesion, without the role of platelet-platelet interactions (aggregation). Platelet adhesion and aggregation were then used to evaluate the thrombogenicity of various artificial surfaces, including silicone rubber and polytetra- fluoroethylene (PTFE) vascular grafts.

Computerized Platelet Aggregation Analysis: A New Method

1979 ◽  
Author(s):  
J.A. Zeller ◽  
R.E. Dayhoff ◽  
R.S. Ledley ◽  
Y.G. Kulkarni
Keyword(s):  
Platelet Aggregation ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Aggregate Size ◽  
Size Group ◽  
Mean Values ◽  
Minute Period ◽  
Size Groups ◽  
Platelet Aggregates ◽  
Aggregation Analysis

Computerized Platelet Aggregation Analysis (CPAA) is a new direct, microscopic methedo-logy using image analysis to quantitate thousands of free platelets and aggregates in platelet rich plasma suspensions and determine the percentage of platelets present in discrete aggregate size groups. CPAA is sensitive to the earliest stages of platelet aggregation which are not recognized by light transmission aggregometry (0% change in light transmission). Platelets of ten normal irxiividuals aged 20-40 years were stimulated by a spin bar (SB) (1100 rpm) for a one minute and a ten minute period. The mean values are shown below for different aggregate size groups.There is no significant increase in the number of aggregates between one and ten mirais of stimulation except for size group 9-40, which shows a minimal increment (P .025). All platelet suspensions contained aggregates of size group 3-8 platelets/aggregate and 4 of 10 specimens had aggregates of size 9-40,No aggregates larger than 41 platelets were found. CPAA can also be applied to the study of larger sized platelet aggregates induced in abnormal individuals.

In Vivo Evaluation of Extended Stored Platelet Concentrates.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 946-946 ◽  
Author(s):  
Sherrill J. Slichter ◽  
Doug Bolgiano ◽  
Jill Corson ◽  
Mary Kay Jones ◽  
Todd Christoffel ◽  
...  
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Storage Conditions ◽  
Mean Value ◽  
Platelet Concentrates ◽  
In Vivo Evaluation ◽  
Platelet Storage ◽  
Volunteer Donor ◽  
Simple Ratio

Abstract Background: With the introduction of bacterial testing, extended storage of platelets is now possible as long as platelet viability is maintained. Although apheresis platelets have recently been licensed for seven days of storage, platelet concentrates are still only licensed for five days. We performed studies to determine the post-storage viability of platelets stored as concentrates. As yet, there are no established criteria for platelet viability that must be met at the end of storage. However, two different criteria for evaluating post-storage platelet viability have been suggested: compare the stored platelet results with each donor’s fresh platelet results; or establish a fixed platelet standard with an expected mean value along with the lower limit of the 95% confidence interval (lower 95% CI) of the mean. Methods: Forty-four normal volunteers donated a unit of whole blood, the whole blood was centrifuged to give platelet-rich plasma (PRP), and the PRP was then centrifuged to produce a platelet concentrate. The platelet concentrates were re-suspended and stored in either 100% plasma or in 20% plasma and 80% Plasmalyte (a platelet storage solution) for five to eight days in Terumo Teruflex bags. At the end of storage, a sample of blood was obtained from each volunteer to prepare fresh platelets to compare the results of a fresh platelet transfusion with the transfusion of the same volunteer’s stored platelets. The fresh and stored platelets were alternately radiolabeled with either 51Cr or 111In, re-injected into their volunteer donor, and serial blood samples were drawn from the volunteer after transfusion of the fresh and stored platelets to determine platelet recoveries and survivals. Results: Results are shown in Table 1. Conclusions: After seven days of storage in plasma, the platelets could qualify for standards of: 74% and 53% as a simple ratio of fresh to stored platelet recoveries and survivals, respectively; according to Dumont’s method of analysis (Transfusion, in press), achievable stored platelet recoveries would be 63% of fresh and survivals would be 40% of fresh; and as a fixed standard, platelet recoveries averaged 45% and survivals 4.4 days with lower 95% CI’s of 35% and 3.3 days, respectively. After eight days of storage in plasma, platelet recoveries and survivals gave unacceptable results. Instead of increasing or at least maintaining post-storage platelet viability, Plasmalyte markedly reduced platelet viability compared to plasma stored platelets at each storage interval. In Vivo Radiolabeled Autologous Platelet Recoveries and Survivals STORAGE CONDITIONS PLATELET RECOVERIES (%) PLATELET SURVIVALS (Days) Solution Time (Days) N Fresh Stored Fresh Stored Data are given as the average ±1 S.D. Plasma 5 10 62±12 55±11 7.7±1.5 6.1±1.0 Plasma 6 10 61±7 46±12 8.2±1.5 5.1±1.6 Plasmalyte 6 3 47±30 29±16 5.1±3.4 1.8±0.2 Plasma 7 10 61±11 45±14 8.3±1.0 4.4±1.5 Plasmalyte 7 5 62±17 30±12 7.4±0.6 2.2±1.1 Plasma 8 3 67±12 31±8 8.3±0.6 2.9±0.8 Plasmalyte 8 3 70±3 21±8 8.2±0.8 0.7±0.1

Quantification of the adhesion of platelets in hamster venules in vivo

1982 ◽  
Vol 215 (1199) ◽  
pp. 135-145 ◽  
Keyword(s):  
Platelet Rich Plasma ◽  
Fluorescein Isothiocyanate ◽  
Adenosine Diphosphate ◽  
Cheek Pouch ◽  
Video Tape ◽  
Flow Through ◽  
Platelet Aggregates ◽  
The Mean ◽  
Adhesion Of Platelets

(i) Citrated platelet-rich plasma freshly prepared from golden hamsters was mixed with fluorescein isothiocyanate (FITC) which made the platelets fluorescent. These platelets were injected intravenously into anaesthetized hamsters with exteriorized cheek pouch preparations superfused at 37 °C with Krebs-bicarbonate solution. The exposed microcirculation was observed microscopically by bright field or fluores­cent illumination. The flowing and sticking of fluorescent platelets was recorded on video tape for quantitative analysis. (ii) In four experiments 22–36%, mean 28%, of fluorescent platelets were circulating 2-3 h after their injection. In seven experiments the fluorescent platelets accounted for 0.6–3.3 %, mean 1.7 %, of circulating platelets. (iii) In venules 20–60 μm in diameter small proportions, mean 5.4%, of circulating fluorescent platelets stopped moving by sticking to the vessel walls. About 80 % of these platelets stuck for up to 1 s, a further 10-15% for up to 5 s, and only about 2% for longer than 2 min. There was an inverse relation between size of venule and proportion of platelets sticking in them. (iv) There was a direct relation between the mean velocities at which platelets flowed through the venules and the sizes of the venules. In the smaller venules the velocity distribution of the platelets had a clear maximum which was not as evident in larger venules. (v) In a few observations on arterioles, flowing platelets could not be seen, and arrested platelets only in a dilatation and at a capillary branch. (vi) Ethylenediamine tetraacetate in the superfusing fluid decreased platelet sticking in venules but did not abolish it. (vii) Adenosine diphosphate in the superfusing fluid caused the appear­ance of platelet aggregates in venules and of sticking platelets in arterioles during progressive diminution in blood flow through both types of vessel. (viii) The observations make it improbable that the release of platelet constituents affects normal venules or arterioles except, possibly, where haemodynamic conditions are affected by wall irregularities such as dilations or branching.

Prevention of in vivo Platelet Aggregation by Indobufen in Angina Patients during Exercise

1981 ◽  
Vol 9 (2) ◽  
pp. 113-119 ◽  
Author(s):  
E M Pogliani ◽  
R Fantasia ◽  
C Perini ◽  
G Corvi
Keyword(s):  
Platelet Aggregation ◽  
Bicycle Ergometer ◽  
Crossover Design ◽  
Double Blind ◽  
Before And After ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates ◽  
Induced Aggregation ◽  
Platelet Functions

Platelet aggregation induced by 3 concentrations of ADP and collagen was assessed in thirty patients with stable angina, before and after exercise with a bicycle ergometer. The patients received a single oral 200 mg dose of indobufen and placebo according to a crossover design in double-blind conditions. Platelet sensitivity to both aggregating agents increased when exercise was carried out after placebo, whereas indobufen markedly inhibited ADP- and collagen-induced aggregation. Circulating platelet aggregates increased in some patients during exercise after placebo but not after indobufen. These results suggest that effort may be an important factor in activation of platelet functions and that the use of drugs blocking the arachidonate pathway and the release reaction may be appropriate in patients with angina.

Influence of Fibrinogen Split Products on Platelets

1967 ◽  
Vol 17 (01/02) ◽  
pp. 078-098 ◽  
Author(s):  
M. I Barnhart ◽  
D. C Cress ◽  
R. L Henry ◽  
J. M Riddle
Keyword(s):  
Platelet Aggregation ◽  
Plasma Concentration ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Platelet Response ◽  
Transient Nature ◽  
Platelet Morphology ◽  
Platelet Aggregates

SummaryBreakdown products of fibrinogen and fibrin can play a role in hemostasis and also may be of consequence in thrombosis. β2 fibrinogen derivative D is an electropositive terminal proteolysis product of fibrinolysis which has the ability to aggregate platelets. The normal plasma concentration of such nonclottable fibrinogen relatives is 0.2 mg/ml. During fibrinolysis this concentration may reach 5 mg/ml plasma. Addition of β 2 fibrinogen D (raising the plasma concentration 0.1 to 5 mg/ml) either in vivo or in vitro induced platelet aggregations. Moreover, alterations in platelet morphology occurred which were obvious by electron microscopy.Platelet depletion was a consistent response to the infusion of purified β2 fibrinogen D (8 to 55 mg/kg body weight) into dogs. Circulating platelets decreased as much as 85% but were only temporarily aggregated and reappeared in the circulation within 1 to 5 hrs. Small platelet aggregates circulated while large aggregates were trapped in the microcirculation. Thrombin was not responsible for the platelet aggregations as neither prothrombin nor clottable fibrinogen were changed significantly. The transient nature and morphological features of the platelet response according to microscopic criteria were prominent during and after infusion of β2 fibrinogen D.In vitro studies included 3 systems; washed platelets, platelet rich plasma and whole blood. Positive results were obtained with all, but platelets in whole blood were most responsive. The magnitude of platelet aggregation and morphology correlated with the concentration of β2 fibrinogen D. Platelet aggregation induced by ADP (10~5 mg/ml) was compared with that induced by β2 fibrinogen D (0.09 to 0.72 mg/ml). With either reagent aggregates were of dendritic forms. Combination of the 2 reagents was additive but did not further change the morphology. Additional factors seem necessary for development of viscous metamorphosis.

Abnormal Platelet Function in Raynaud’s Phenomenon.

1979 ◽  
Author(s):  
J. Zahavi ◽  
W.A.P. Hamilton ◽  
M.J.G. O’Reilly ◽  
S.E. Clark ◽  
L.T. Cotton ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Healthy Subjects ◽  
Platelet Rich Plasma ◽  
Raynaud’S Phenomenon ◽  
Adenosine Diphosphate ◽  
Raynaud's Phenomenon ◽  
Plasma Fibrinogen ◽  
Serum Immunoglobulin ◽  
Plasma Factors

Platelet aggregation (PA) induced by adenosine diphosphate (ADP) 0.6 and 4μM, 1-ephinephrine 6μM, collagen lu/ml and thrombin 0.2u/ml has been measured in citrated platelet rich plasma of 38 patients (mean age 42.2) suffering from Raynaud’s Phenomenon. In 29 of them, plasma β-thromboglobulin (βTG), measured by radioimmunoassay was determined and the results were compared to age and sex matched healthy subjects and correlated to serum immunoglobulin (Ig) and plasma fibrinogen levels. Plasma βTG (mean 72.2ng/ml, ranged 20-209) was significantly elevated in the patients compared to the controls (p ≤ 0.005). The rate and extent of platelet aggregation however, though higher in the patients than controls were significant only to ADP 0.6μM (p ≤ 0.045) rate and p ≤ 0.002 extent) and 4μM (p ≤ 0.005 rate and p ≤ 0.004 extent). Serum IgM levels were also abnormally increased in 12, IGA in one and IgG in 4 patients. There was no correlation between the platelet studies are plasma fibrinogen or serum immunoglobulin suggesting that these tests are measuring various aspects of the disease state. These results indicate that in-vivo platelet activation and “release reaction” are enhanced in patients suffering from Raynaud’s Phenomenon presumably not only by abnormal plasma factors. Furthermore, they suggest that platelets may be involved in the pathogenesis of the disease and its complications.

scholarly journals Wound Healing: In Vitro and In Vivo Evaluation of a Bio-Functionalized Scaffold Based on Hyaluronic Acid and Platelet-Rich Plasma in Chronic Ulcers

2019 ◽  
Vol 8 (9) ◽  
pp. 1486 ◽  
Author(s):  
Barbara De Angelis ◽  
Margarida Fernandes Lopes Morais D’Autilio ◽  
Fabrizio Orlandi ◽  
Giampiero Pepe ◽  
Simone Garcovich ◽  
...  
Keyword(s):  
Wound Healing ◽  
Hyaluronic Acid ◽  
Platelet Rich Plasma ◽  
Combined Treatment ◽  
Skin Grafting ◽  
Control Group ◽  
In Vivo Evaluation ◽  
Chronic Ulcers

Chronic ulcers are characterized by loss of substance without a normal tendency towards spontaneous healing. The Wound Bed Preparation Guideline advises that after diagnosis, the expert should correct the biological state of the ulcer micro-environment based on TIME principles (Tissue, Infection, Moisture balance, Epidermal). There are many ways to treat such ulcers, for example through use of advanced dressings, negative pressure, surgical toilets, dermal substitutes, autologous skin grafting, and free or local flaps. In vitro and in vivo pre-clinical models hold widely acknowledged potential yet complex limitations. Tissue bioengineering could be an ideal approach to foster innovative strategies in wound healing. Our observational study reports on an in vitro and in vivo evaluation of a bio-functionalized scaffold composed of platelet-rich plasma (PRP) and hyaluronic acid (HA) used in 182 patients affected by chronic ulcers (diabetic and vascular), comparing the results with a control group of 182 patients treated with traditional dressings (HA alone). After 30 days the patients who had undergone the combined treatment (PRP + HA), showed 96.8% ± 1.5% re-epithelialization, as compared to 78.4% ± 4.4% in the control group (HA only). Within 80 days, they had 98.4% ± 1.3% re-epithelialization as compared to 87.8% ± 4.1% in the control group (HA only; p < 0.05). No local recurrence was observed during the follow-up period. PRP + HA treatment showed stronger regenerative potential in terms of epidermal proliferation and dermal renewal compared with HA alone.

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