A Radioimmunoassay for Human Platelet β-Thromboglobulin

1975 ◽  
Author(s):  
C. A. Ludlam ◽  
A. E. Bolton
Keyword(s):  
Whole Blood ◽  
Heart Valves ◽  
Plasma Concentrations ◽  
Human Platelets ◽  
Prosthetic Heart Valves ◽  
Platelet Poor Plasma ◽  
Release Reaction ◽  
Assay Conditions

β-thromboglobulin (βtg) is a protein recently isolated from human platelets. A radioimmunoassay for βtg has been established.Using this assay, conditions have been defined for the preparation of platelet poor plasma, so as to minimise the liberation of βtg during manipulations in vitro. Platelet poor plasma prepared from whole blood, collected in EDTA, prostaglandin E9, and theophylline, and centrifuged at 0°C., contained 0.019±0.0075 μg ml−1 (mean±l SD). Serum prepared from clotted whole blood (in which platelets had undergone the release reaction) had a concentration of 17.4±6.3 μg ml−1, while plasma from platelet transfusion concentrates contained 247.0±120.3 μg ml−1. There was no increase in βtg concentration when platelet poor plasma was clotted by the addition of calcium. The presence of a 1000-fold difference between plasma and serum concentrations, the observed release following collagen induced platelet aggregation in vitro, and the observations that other human tissues contained only trace amounts suggests that βtg is unique to platelets.Preliminary clinical studies have shown that patients with acute arterial thrombosis and others with prosthetic heart valves have raised plasma concentrations. It is possible, therefore, that this assay has potential uses for studying the platelet release reaction in vitro, and also the identification of individuals with excessive platelet sequestration in vivo.

scholarly journals Survival and recovery of human platelets stored for five days in a non- plasma medium

Blood ◽  
1986 ◽  
Vol 67 (3) ◽  
pp. 672-675 ◽  
Author(s):  
GA Adams ◽  
SD Swenson ◽  
G Rock
Keyword(s):  
Platelet Aggregation ◽  
Human Blood ◽  
Blood Platelets ◽  
Human Platelets ◽  
Plasma Medium ◽  
Release Reaction ◽  
In Vivo Recovery ◽  
Human Blood Platelets

Abstract Human blood platelets were stored for five days as concentrates in 60 mL of: (a) plasma; (b) non-plasma medium with anticoagulant; and (c) non-plasma medium without anticoagulant. All preparations were equally functional when tested for platelet aggregation and release reaction in response to single agonist or synergistic pairs of agonists in vitro. Platelets stored in non-plasma medium with anti-coagulant had lower kallikrein, fibrino(gen)peptide A, lactate, and beta-thromboglobulin than did plasma controls after five days. In vivo recovery and survival of platelets stored in non-plasma medium with anticoagulant were 51.2% +/- 4.3% and 8.7 +/- 0.3 days, respectively, which were not statistically different from plasma controls of 39.2% +/- 4.9% and 7.2 +/- 0.8 days, respectively. It is concluded that platelets can be stored for five days in a non-plasma medium and still have good in vivo recoveries and survivals.

scholarly journals Comparative Studies of Platelet Survival by Different Methods in the Rabbit

Blood ◽  
1965 ◽  
Vol 25 (4) ◽  
pp. 548-566 ◽  
Author(s):  
SHIRLEY EBBE ◽  
MARIO BALDINI ◽  
JANET DONOVAN
Keyword(s):  
Survival Time ◽  
Whole Blood ◽  
Comparative Studies ◽  
Significant Degree ◽  
Human Platelets ◽  
Sodium Chromate ◽  
Platelet Concentrates ◽  
Rabbit Platelets

Abstract Four methods for measuring the survival of homologous platelets in rabbits were studied: (1) transfusion of nonradioactive platelet concentrates to thrombocytopenic recipients, (2) transfusion of concentrates of platelets labeled in vitro with Cr51-sodium chromate, (3) transfusion of concentrates of platelets labeled in vivo with P32-orthophosphate and (4) transfusion of whole blood labeled in vivo with P32-orthophosphate. The survival time of platelets in normal rabbits was 3-4 days. From comparison of the 3 methods using platelet concentrates, the following conclusions were drawn. (1) All the platelets in a platelet concentrate were capable of recirculating after transfusion. (2) Labeling with P32 or Cr51 did not damage platelets. (3) About one-third of the Cr51 was immediately eluted from viable platelets after they were transfused. (4) Further exchange of the label in vivo did not occur to a significant degree with either Cr51 or P32. (5) Cr51 did not elute from platelets during storage of the platelets. (6) Studies of rabbit platelets had applicability in predicting the behavior of human platelets.

scholarly journals SIBS triblock copolymers in cardiac surgery: in vitro and in vivo studies in comparison with ePTFE

2020 ◽  
Vol 21 (4) ◽  
pp. 67-80
Author(s):  
M. A. Rezvova ◽  
E. A. Ovcharenko ◽  
P. A. Nikishev ◽  
S. V. Kostyuk ◽  
L. V. Antonova ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Heart Valves ◽  
Ex Vivo ◽  
Calcium Content ◽  
Positive Control ◽  
Prosthetic Heart Valves ◽  
Solution Casting Method ◽  
Cell Adhesion And Proliferation

Implantation of polymeric heart valves can solve the problems of existing valve substitutes – mechanical and biological. Objective: to comprehensively assess the hemocompatibility of styrene-isobutylene-styrene (SIBS) triblock copolymer, synthesized by controlled cationic polymerization in comparison with expanded polytetrafluoroethylene (ePTFE) used in clinical practice. Materials and methods. SIBS-based films were made by polymer solution casting method; in vitro biocompatibility assessment was performed using cell cultures, determining cell viability, cell adhesion and proliferation; tendency of materials to calcify was determined through in vitro accelerated calcification; in vivo biocompatibility assessment was performed by subcutaneous implantation of rat samples; hemocompatibility was determined ex vivo by assessing the degree of hemolysis, aggregation, and platelet adhesion. Results. The molecular weight of synthesized polymer was 33,000 g/mol with a polydispersity index of 1.3. When studying cell adhesion, no significant differences (p = 0.20) between the properties of the SIBS polymer (588 cells/mm2) and the properties of culture plastics (732 cells/mm2) were discovered. Cell adhesion for the ePTFE material was 212 cells/mm2. Percentage of dead cells on SIBS and ePTFE samples was 4.40 and 4.72% (p = 0.93), respectively, for culture plastic – 1.16% (p < 0.05). Cell proliferation on the ePTFE surface (0.10%) was significantly lower (p < 0.05) than for the same parameters for SIBS and culture plastic (62.04 and 44.00%). Implantation results (60 days) showed the formation of fibrous capsules with average thicknesses of 42 μm (ePTFE) and 58 μm (SIBS). Calcium content in the explanted samples was 0.39 mg/g (SIBS), 1.25 mg/g (ePTFE) and 93.79 mg/g (GA-xenopericardium) (p < 0.05). Hemolysis level of red blood cells after contact with SIBS was 0.35%, ePTFE – 0.40%, which is below positive control (p < 0.05). Maximum platelet aggregation of intact platelet-rich blood plasma was 8.60%, in contact with SIBS polymer – 18.11%, with ePTFE – 22.74%. Conclusion. In terms of hemocompatibility properties, the investigated SIBS polymer is not inferior to ePTFE and can be used as a basis for development of polymeric prosthetic heart valves.

Inhibitory Effect of Piracetam on Platelet-rich Thrombus Formation in an Animal Model

1998 ◽  
Vol 79 (01) ◽  
pp. 222-227 ◽  
Author(s):  
F. Stockmans ◽  
W. Deberdt ◽  
Å. Nyström ◽  
E. Nyström ◽  
J. M. Stassen ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ex Vivo ◽  
Peak Plasma ◽  
Thrombus Formation ◽  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Cell Deformability

SummaryIntravenous administration of piracetam to hamsters reduced the formation of a platelet-rich venous thrombus induced by a standardised crush injury, in a dose-dependent fashion with an IC50 of 68 ± 8 mg/kg. 200 mg/kg piracetam also significantly reduced in vivo thrombus formation in rats. However, in vitro aggregation of rat platelets was only inhibited with piracetam-concentrations at least 10-fold higher than plasma concentrations (6.2 ± 1.1 mM) obtained in the treated animals. No effects were seen on clotting tests.In vitro human platelet aggregation, induced by a variety of agonists, was inhibited by piracetam, with IC50’s of 25-60 mM. The broad inhibition spectrum could be explained by the capacity of piracetam to prevent fibrinogen binding to activated human platelets. Ex vivo aggregations and bleeding times were only minimally affected after administration of 400 mg/kg piracetam i.v. to healthy male volunteers, resulting in peak plasma levels of 5.8 ± 0.3 mM.A possible antiplatelet effect of piracetam could be due to the documented beneficial effect on red blood cell deformability leading to a putative reduction of ADP release by damaged erythrocytes. However similarly high concentrations were needed to prevent stirring-induced “spontaneous” platelet aggregation in human whole blood.It is concluded that the observed antithrombotic action of piracetam cannot satisfactorily be explained by an isolated direct effect on platelets. An additional influence of piracetam on the rheology of the circulating blood and/or on the vessel wall itself must therefore be taken into consideration.

The Potentiation of Platelet Aggregation and Adhesion by Heparin in Vitro and in Vivo

1973 ◽  
Vol 45 (4) ◽  
pp. 485-494 ◽  
Author(s):  
C. Thomson ◽  
C. D. Forbes ◽  
C. R. M. Prentice
Keyword(s):  
Platelet Aggregation ◽  
Intravenous Injection ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Test Cell ◽  
Release Reaction ◽  
Platelet Release ◽  
Increase Platelet Aggregation

1. Heparin has been shown to increase platelet aggregation by ADP and adrenaline and to enhance the platelet release reaction when tested in citrated platelet-rich plasma (P.R.P.). This activity is present when heparin is added to P.R.P. or when P.R.P. is prepared after intravenous injection of heparin, and when heparin is added to non-anticoagulated native P.R.P. 2. Retention of platelets by cellophane membranes within a specially designed test-cell was significantly increased when heparin was added to citrated whole blood. 3. Though aspirin blocks the release reaction with and without heparin, it does not prevent the potentiation of initial ADP or first wave adrenaline aggregation caused by heparin.

scholarly journals Survival and recovery of human platelets stored for five days in a non- plasma medium

Blood ◽  
1986 ◽  
Vol 67 (3) ◽  
pp. 672-675 ◽  
Author(s):  
GA Adams ◽  
SD Swenson ◽  
G Rock
Keyword(s):  
Platelet Aggregation ◽  
Human Blood ◽  
Blood Platelets ◽  
Human Platelets ◽  
Plasma Medium ◽  
Release Reaction ◽  
In Vivo Recovery ◽  
Human Blood Platelets

Human blood platelets were stored for five days as concentrates in 60 mL of: (a) plasma; (b) non-plasma medium with anticoagulant; and (c) non-plasma medium without anticoagulant. All preparations were equally functional when tested for platelet aggregation and release reaction in response to single agonist or synergistic pairs of agonists in vitro. Platelets stored in non-plasma medium with anti-coagulant had lower kallikrein, fibrino(gen)peptide A, lactate, and beta-thromboglobulin than did plasma controls after five days. In vivo recovery and survival of platelets stored in non-plasma medium with anticoagulant were 51.2% +/- 4.3% and 8.7 +/- 0.3 days, respectively, which were not statistically different from plasma controls of 39.2% +/- 4.9% and 7.2 +/- 0.8 days, respectively. It is concluded that platelets can be stored for five days in a non-plasma medium and still have good in vivo recoveries and survivals.

Interaction of Platelets with Model Surfaces III: Platelet Reaction with Synthetic Polymers

1975 ◽  
Author(s):  
J. N. Lindon ◽  
D. Brier ◽  
E. W. Merrill ◽  
E. W. Salzman
Keyword(s):  
Whole Blood ◽  
Platelet Adhesion ◽  
Pyrolytic Carbon ◽  
Coagulation Factors ◽  
Surface Reactivity ◽  
Material Surface ◽  
Release Reaction ◽  
Variable Surface

Blood/material surface interactions have been studied by passing citrated whole blood over beads in a column and examining the resultant activation of platelets and coagulation factors. Examination of many polymer and some crystalline surfaces indicates that platelet adhesion occurs with all surfaces except after pretreatment with albumin in some instances. Induction of the platelet release reaction and platelet adhesion vary from one surface to another and are not well correlated. The release reaction in response to some but not all surfaces can be blocked by pretreatment of blood with aspirin in vivo and indomethacin in vitro. PRP exhibits less activation than whole blood, but varying the hematocrit of whole blood from 23 to 53% does not change surface reactivity.Of the materials studied, polyethylacrylate (PEA) and polymethylacrylate (PMA) appear least reactive. Certain materials, e.g. polystyrene and polyvinylacetate, exhibit variable surface reactivity with different blood samples, while others, e.g. pyrolytic carbon and PMA, produce a uniform response. A general trend appears to be less surface reactivity with decreasing glass transition temperature. Chemical modification of polymers and production of copolymers has been undertaken to define the nature of reactive sites. For example, acrylonitrile and aminomethylacrylate copolymers of PMA exhibit more reactivity than PMA.Sepharose 4B (4% agarose gel beads) appears essentially non-reactive. However, Sepharose with covalently bound heparin promotes extensive platelet adhesion. Pretreatment of this surface with increasing amounts of plasma, but not albumin, produces decreasing surface reactivity.

Characterization of red blood cell metabolism in rainbow trout

1990 ◽  
Vol 154 (1) ◽  
pp. 475-489 ◽  
Author(s):  
P. J. Walsh ◽  
C. M. Wood ◽  
S. Thomas ◽  
S. F. Perry
Keyword(s):  
Rainbow Trout ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Whole Blood ◽  
Cell Metabolism ◽  
Plasma Concentrations ◽  
Co2 Production ◽  
Production Rates

Red blood cell metabolism was studied in vitro using whole blood obtained by catheter from resting rainbow trout (Oncorhynchus mykiss). Preparations were viable as shown by stable NTP, metabolite and catecholamine levels and acid-base status, all of which remained at in vivo levels over the 2 h incubation period. Enzymes diagnostic of glycolysis, the tricarboxylic acid (TCA) cycle and phosphagen metabolism were all present in significant amounts in red blood cells. In direct comparisons of 14C-labelled substrates at normal resting plasma concentrations, rates of CO2 production were in the order: glucose greater than lactate greater than alanine greater than oleate. Total CO2 production rates from these four oxidative substrates did not equal directly measured O2 consumption rates, indicating that other substrates may also be important in vivo. Oxidative pathway Km values for glucose (8.4 mmol l-1), lactate (3.3 mmol l-1) and alanine (0.8 mmol l-1) were well within the normal physiological ranges of plasma concentrations. Glucose concentration did not affect lactate oxidation rates, but there was some inhibition (27%) of glucose oxidation by high lactate concentrations (20 mmol l-1). The observed Km values and competitive interactions suggest that changes in plasma concentrations associated with environmental stresses can considerably alter the relative rates of oxidation of glucose and lactate in vivo. Considerable pentose-phosphate shunt activity was detected in red cells, as indicated by high activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase and high CO2 production rates from (1–14C)-labelled glucose. Even in the presence of normal O2 levels, a significant percentage (28%) of glucose metabolism was directed to lactate production. Taken together, these results demonstrate that rainbow trout whole blood incubated in vitro constitutes a dynamic and viable system for metabolic studies at the pathway level.

Stress Corrosion Cracking in Björk-Shiley Convexo-Concave Prosthetic Heart Valves Due to Random in vivo Electrochemical Pulsing

1996 ◽  
Vol 19 (8) ◽  
pp. 477-486 ◽  
Author(s):  
K. Xiao ◽  
A.J. Appleby
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Heart Valves ◽  
Pyrolytic Carbon ◽  
Open Circuit ◽  
Corrosion Cracking ◽  
Prosthetic Heart Valves ◽  
Weld Area

Welded downstream struts of Björk-Shiley Convexo-Concave heart valves show failure in vivo, but not in in vitro testing. A pyrolytic carbon pivoting disk occluder closes against a Haynes® 25 alloy ring, which is electrochemically machined from solid with the upstream retaining struts. The weld area is de-alloyed, with residual porosity and carbide inclusions. The valve becomes a short-circuited electrochemical cell when fully open or closed. It is in an aggressive chloride electrolyte, whose high pulsed flow (2 m/s) ensures that supply of oxygen-rich cathode reactant is not mass-transport-limited. During the flight of the occluder, the cell is randomly at open circuit. A random current pulse is applied to the metal parts on circuit closure. Failure is not from simple mechanical fatigue, but from stress-corrosion-cracking and erosion of the less noble weld area caused by these pulses. All welded valves of this type may be susceptible to ultimate in vivo failure.

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