Sources of Variability in Dose Response Platelet Aggregometry

1985 ◽  
Vol 53 (02) ◽  
pp. 219-220 ◽  
Author(s):  
M V Vickers ◽  
S G Thompson
Keyword(s):  
Dose Response ◽  
Maximum Velocity ◽  
Adenosine Diphosphate ◽  
Method Error ◽  
Platelet Aggregability ◽  
Differential Effects ◽  
Platelet Aggregometry ◽  
Simultaneous Comparison ◽  
Aggregation Parameters ◽  
Very High

SummaryAn experiment designed to assess the components of variability of a number of measures of platelet aggregability showed that the ADP ED50 (the estimated dose of adenosine diphosphate at which primary aggregation occurs at half its maximum velocity) had the least method error of any of the parameters measured, but that none had a very high between-person component of variability. A simultaneous comparison of a syringe technique and a free-flowing technique for venepuncture revealed no differential effects on the aggregation parameters measured. An enforced increase in the stirring speed in the aggregometer led to an experiment which showed that such a change did not apparently affect the ED50s.

Methods in Dose Response Platelet Aggregometry

1985 ◽  
Vol 53 (02) ◽  
pp. 216-218 ◽  
Author(s):  
S G Thompson ◽  
M V Vickers
Keyword(s):  
Quality Control ◽  
Heart Disease ◽  
Dose Response ◽  
Response Rate ◽  
Large Prospective Study ◽  
Platelet Aggregability ◽  
Aggregation Response ◽  
Platelet Aggregometry ◽  
Sigmoid Curve

SummaryA standardized method for performing dose response platelet aggregation has been developed, and has been used in about 1000 subjects in a large prospective study of ischaemic heart disease. A computer program has been used to fit a sigmoidal relationship between primary aggregation response rate and the log dose of aggregating reagent. Estimates of the parameters of the sigmoid curve are used to characterize an individual’s platelet aggregability. Methods for investigating the maintenance of long-term quality control have also been developed.

DEVELOPMENT OF NACL-BASED OPTICALLY STIMULATED LUMINESCENT PHOSPHORS FOR THE POSSIBLE APPLICATIONS IN DOSIMETRY

2020 ◽  
Vol 192 (1) ◽  
pp. 27-35
Author(s):  
S U Gaikwad ◽  
R R Patil ◽  
M S Kulkarni ◽  
C M Dudhe ◽  
S V Moharil
Keyword(s):  
Dose Response ◽  
Radiation Dosimetry ◽  
Optically Stimulated Luminescence ◽  
Signal Loss ◽  
Highly Sensitive ◽  
Very High

Abstract New highly sensitive optically stimulated luminescent phosphors with NaCl moiety and dopants Ca,Cu,P/Mg,Cu,P are developed. These phosphors show very high optically stimulated luminescence (OSL) sensitivity. The dose response for NaCl:Ca,Cu,P is linear up to 1.2 Gy and for NaCl:Mg,Cu,P is slightly sub linear from 0.2 Gy. These phosphors show 30% fading during first 4 and later signal gets stabilised with no further signal loss. These sensitive phosphors will find applications in radiation dosimetry using OSL.

Dose-response and histopathological study, with special attention to the hypophysis, of the differential effects of domoic acid on rats and mice

2015 ◽  
Vol 78 (5) ◽  
pp. 396-403 ◽  
Author(s):  
Andrés Crespo Vieira ◽  
J. Manuel Cifuentes Martínez ◽  
Roberto Bermúdez Pose ◽  
Álvaro Antelo Queijo ◽  
Nuria Alemañ Posadas ◽  
...  
Keyword(s):  
Dose Response ◽  
Domoic Acid ◽  
Histopathological Study ◽  
Differential Effects ◽  
Rats And Mice

scholarly journals Factor VIII-induced superaggregation of human platelets

Blood ◽  
1982 ◽  
Vol 60 (6) ◽  
pp. 1359-1369 ◽  
Author(s):  
EP Kirby ◽  
DC Mills ◽  
H Holmsen ◽  
M Russo
Keyword(s):  
Factor Viii ◽  
Cytochalasin B ◽  
Dextran Sulfate ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Ionophore A23187 ◽  
High Concentrations ◽  
Induced Aggregation ◽  
Very High ◽  
Bovine Factor

Abstract High concentrations of bovine factor VIII cause clumping of platelets into a few very large aggregates. This response is termed superaggregation. It is distinct from factor-VIII-induced agglutination but is also independent of both extracellular calcium ions and platelet energy metabolism. Neither agglutinating lectins nor aggregating agents, including thrombin, ADP, the ionophore A23187, and U46619, a prostaglandin analog, can induce superaggregation, even at very high concentrations. Washed platelets undergo superaggregation, and superaggregation does not increase the amounts of fibrinogen or albumin trapped by agglutinated platelets. It is not inhibited by membrane- stabilizing drugs or by colchicine or cytochalasin-B. Formaldehyde and glutaraldehyde prevent superaggregation without affecting the binding of radiolabeled factor VIII to the platelets. Superaggregated platelets are separated by approximately 50 nm and are not shape-changed or degranulated. In adenosine diphosphate (ADP) induced aggregation, the platelets are distorted and only 30 nm apart. Superaggregation is reversed by dextran sulfate, and the dispersed platelets are still able to respond to ADP. Our observations are consistent with the binding of high molecular weight multimers of bovine factor VIII to more than one receptor on each platelet, with superaggregation occurring through recruitment of additional receptors. This process may be interrupted by protein crosslinking reagents, such as formaldehyde and glutaraldehyde.

scholarly journals DEM simulation of cyclic tests on an offshore screw pile for floating wind

2021 ◽  
Author(s):  
Wei Wang ◽  
◽  
Michael Brown ◽  
Matteo Ciantia ◽  
Yaseen Sharif ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Maximum Velocity ◽  
Uplift Capacity ◽  
Cyclic Performance ◽  
Cyclic Tests ◽  
High Demand ◽  
Dem Simulation ◽  
Screw Pile ◽  
Physical Tests ◽  
Very High

Screw piles need to be upscaled for offshore use e.g. being an alternative foundation and anchor form for offshore floating wind turbines, although the high demand of vertical installation forces could prevent its application if conventional pitch-matched installation is used. Recent studies, using numerical and centrifuge physical tests, indicated that the vertical installation force can be reduced by adopting over-flighting which also improved axial uplift capacity of the screw pile. The current study extends the scope to axial cyclic performance with respect to the installation approach. Using quasi-static discrete element method (DEM) simulation it was found that the over-flighted screw pile showed a lower displacement accumulation rate, compared to a pitch-matched installed pile, in terms of load-controlled cyclic tests. Sensitivity analysis of the setup of the cyclic loading servo shows the maximum velocity during the tests should be limited to avoid significant exaggeration of the pile displacement accumulation but this may lead to very high run durations.

scholarly journals Correlation between fibrinogen binding to human platelets and platelet aggregability

Blood ◽  
1980 ◽  
Vol 55 (5) ◽  
pp. 841-847 ◽  
Author(s):  
EI Peerschke ◽  
MB Zucker ◽  
RA Grant ◽  
JJ Egan ◽  
MM Johnson
Keyword(s):  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Fibrinogen Concentration ◽  
Platelet Aggregability ◽  
Single Receptor ◽  
Fibrinogen Binding ◽  
Fibrinogen Molecule ◽  
Bernard Soulier Syndrome

Fibrinogen is essential for aggregating platelets with adenosine diphosphate (ADP) and was recently shown to bind to platelets stimulated with ADP. The present work confirms the specific and saturable nature of the platelet-fibrinogen interaction. Binding of 125iodine-labeled fibrinogen to human gel-filtered platelts was maximal at 1 min, and the receptors were saturated when the fibrinogen concentration in the suspending medium approached 0.8 mg/ml. Assuming that one fibrinogen molecule interacts with a single receptor, experiments with 9 normal donors revealed the presence of 12,896 +/- 2456 receptors per platelet. Much of the bound material dissociated from platelets after incubation with apyrase or EDTA. Binding was markedly inhibited at pH 6.5, in the presence of EDTA, and with platelets from 3 thrombasthenic patients but not with those from a patient with the Bernard-Soulier syndrome. Fibrinogen binding was also virtually absent with platelets that had been incubated with EDTA for 8 min at 37 degrees C and pH 7.8. These platelets could not aggregate when mixed with ADP and adequate CaCl2 and fibrinogen, although they could still change their shape. Thus, ADP-induced binding of fibrinogen correlates with platelet aggregability.

scholarly journals Musculoskeletal pain intensity in different body regions and risk of disability pension among female eldercare workers: prospective cohort study with 11-year register follow-up

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Rúni Bláfoss ◽  
Jonas Vinstrup ◽  
Sebastian Venge Skovlund ◽  
Rubén López-Bueno ◽  
Joaquin Calatayud ◽  
...  
Keyword(s):  
Risk Factor ◽  
Pain Intensity ◽  
Labour Market ◽  
Musculoskeletal Pain ◽  
Dose Response ◽  
Disability Pension ◽  
Low Back ◽  
Body Regions ◽  
Very High

Abstract Background Musculoskeletal pain is a risk factor for leaving the labour market temporarily and permanently. While the presence of multi-site pain increases the risk of disability pension, we lack detailed knowledge about pain intensity as a risk factor. This study investigated the association between musculoskeletal pain intensity in different body regions and risk of future disability pension among eldercare workers. Methods Eight thousand seven hundred thirty-one female eldercare workers replied to a questionnaire on work and health in 2005 and were followed for 11 years in the Danish Register for Evaluation of Marginalization. Time-to-event analyses estimated hazard ratios (HR) for disability pension from pain intensities (0–9 numeric rating scale (NRS)) in the low-back, neck/shoulders, and knees during the previous 3 months. Analyses were mutually adjusted for pain regions, age, education, lifestyle, psychosocial work factors, and physical exertion at work. Results During 11-year follow-up, 1035 (11.9%) of the eldercare workers received disability pension. For all body regions among all eldercare workers, dose-response associations were observed between higher pain intensity and risk of disability pension (p < 0.001). The risk for disability pension was increased when reporting “very high” pain levels (≥7 points on the 0–9 NRS) in the low-back (HR 2.19, 95% CI 1.70–2.82), neck/shoulders (HR 2.34, 95% CI 1.88–2.92), and knees (HR 1.89, 95% CI 1.44–2.47). Population attributable risks (PAR) were 15.5, 23.2, and 9.6% for pain > 2 on NRS in the low-back, neck/shoulders, and knees, respectively, indicating that 15.5, 23.2, and 9.6% fewer eldercare workers would likely receive disability pension if the pain intensity was reduced to 2 or less. For workers ≤45 years and > 45 years, PAR was highest for neck/shoulder pain (27.6%) and low-back pain (18.8%), respectively. Conclusions The present study found positive dose-response associations between pain intensity in the low-back, neck/shoulders, and knees, and risk of disability pension during 11-year follow-up. Moderate to very high levels of musculoskeletal pain in eldercare workers should, therefore, be considered an early warning sign of involuntary premature exit from the labour market. These findings underscore the importance of preventing, managing, and reducing musculoskeletal pain to ensure a long and healthy working life.

COMPUTERIZED PLATELET AGGREGOMETRY

1987 ◽  
Author(s):  
T Szabados ◽  
F Hermán ◽  
G Kollányi ◽  
P Hadházy ◽  
K Magyar
Keyword(s):  
Dose Response ◽  
In Vitro Tests ◽  
Response Curves ◽  
Dual Channel ◽  
Large Numbers ◽  
Platelet Aggregometry ◽  
Enormous Amount ◽  
Dose Response Curves ◽  
The Individual

One of the commonly used in vitro tests for assessing platelet function is a photodensitometric assay first established by Born. However the collection and analysis of aggregation data are tedious and time consuming. The single- and dual-channel aggregometers have limited utility for the analysis of large numbers of plasma samples in clinical laboratories or in studies on the mode of action of drugs.We now report on a multichannel platelet aggregome-ter system consisting of an IBM XT personal computer and three microprocessor-controlled 4 channel aggregometers. The system collects, displays and analyzes 12 different aggregation curves simultaneously, and - like other computerized systems - (1) significantly increa ses the efficiency and ease in performing the experiment, analyzing and presenting the data; (2) provides systematic storage and rapid retrieval of the data;(3) saves an enormous amount of time; (4) because of multichannel capability eliminates the effects of time-related changes in PRP on the dose-response curves.However our system has some advantages over the computerized aggregometer systems used so far: (1) since the aggregometers contain built in microprocessors they can be utilized to measure and analyse platelet aggregation without being coupled to a computer; (2) a special program helps to check the validity of the calculated parameters under visual control; (3) the individual points of the dose-response curves can be checked at any time during the experiment.

Reduced platelet aggregability and thromboxane release after rebleeding in patients with subarachnoid hemorrhage

1991 ◽  
Vol 74 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Seppo Juvela ◽  
Marrku Kaste
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Statistical Significance ◽  
Adenosine Diphosphate ◽  
Blood Samples ◽  
Content Type ◽  
Platelet Aggregability ◽  
Before And After ◽  
Fine Print

✓ Serial blood samples were obtained from 80 patients with subarachnoid hemorrhage (SAH) to study adenosine diphosphate-induced platelet aggregation and associated thromboxane B2 release. The goal of the investigation was to detect whether reduced platelet function is involved in rebleeds. Seventeen patients (21%) suffered a rebleed, six of those experiencing their first rebleed within 24 hours after SAH. Therefore, most platelet function studies were performed after rebleeds. Thromboxane release was lower in patients with rebleeds than in the others, both before and after rebleeding, although statistical significance was reached only in samples collected after rebleeds. Patients rebleeding within 24 hours after SAH had lower platelet aggregability (p = 0.037) than patients without a rebleed in the samples taken within 3 days after SAH. The results suggest that reduced platelet aggregability and thromboxane release are involved in rebleeds following primary SAH.

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