Abstract 19437: Elevated Platelet Turnover in Patients Receiving Dual Antiplatlet Therapy Could Permit the Formation of Uninhibited Platelet Clusters That Act as Seeds for Thrombus Formation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Thomas Hoefer ◽  
Timothy D Warner
Keyword(s):  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Imaging Techniques ◽  
Once Daily ◽  
Increased Risk ◽  
Light Transmission Aggregometry ◽  
Platelet Aggregates ◽  
Dynamic Relationships ◽  
Drug Free

Introduction: ACS patients who also have conditions associated with increased platelet turnover, such as diabetes or chronic kidney disease, are at increased risk of atherothrombotic events despite receiving dual-antiplatelet therapy (DAPT). It may well be that aspirin and thienopyridines, such as clopidogrel or prasugrel, prescribed once daily as pharmacologically short-lived but irreversibly acting agents, are less effective in these patients because of the daily emergence of a significant subpopulation of uninhibited platelets. Hypothesis: Here we investigated the potentially crucial roles of subpopulations of uninhibited platelets in overcoming DAPT and driving aggregation. Methods: Aliquots of platelet rich plasma were incubated with aspirin, prasugrel active metabolite (PAM) plus aspirin, or vehicle and platelets were differently labelled with membrane dyes. Aliquots were then combined in various proportions and platelet responses measured in standard light transmission aggregometry. Aggregates formed in response to platelet agonists were then fixed and detailed structural analyses made by advanced imaging techniques, including confocal microscopy and ImageStream flow cytometry, to determine the interactions of different platelet populations. Results: Platelet aggregation responses and images of platelet aggregates demonstrated complex, dynamic relationships between platelet subpopulations. Summary analysis indicated that aggregates containing aspirin-treated (90-60%) and drug-free (10-40%) platelets had random distributions of drug-free platelets in response to ADP or AA. In contrast, aggregates containing DAPT-inhibited (90-60%) platelets and drug-free (10-40%) platelets showed marked clustering of drug-free platelets at aggregate cores surrounded by recruited DAPT-inhibited platelets. Conclusions: We show that a subpopulation of drug-free platelets can provide seeds for the formation of aggregates that then recruit DAPT-inhibited platelets. Such interaction between platelet subpopulations are of direct relevance to ACS patients with underlying conditions associated with elevated platelet turnover and may well provide an explanation for the failure of DAPT with aspirin and thienopyridines.

Lack of Stability of Aggregates after Thrombin-Induced Reaggregation of Thrombin-Degranulated Platelets

1992 ◽  
Vol 67 (04) ◽  
pp. 453-457 ◽  
Author(s):  
Raelene L Kinlough-Rathbone ◽  
Marian A Packham ◽  
Dennis W Perry ◽  
J Fraser Mustard ◽  
Marco Cattaneo
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Aggregate Stability ◽  
Relative Importance ◽  
Platelet Aggregates ◽  
The Stability ◽  
Von Willebrand ◽  
Induced Aggregation ◽  
Willebrand Factor

SummaryThe stability of platelet aggregates is influenced by the extent of the release of granule contents; if release is extensive and aggregation is prolonged, deaggregation is difficult to achieve. The relative importance of the contributions of released substances to aggregate stability are not known, although stable thrombin-induced aggregates form in platelet-rich plasma from patients with barely detectable plasma or platelet fibrinogen, and ADP stabilizes thrombin-induced aggregates of platelets from patients with delta storage pool deficiency which otherwise deaggregate more readily than normal platelets. We degranulated platelets with thrombin (0.9 U/ml caused greater than 90% loss of delta and alpha granule contents) and recovered them as individual platelets in fresh medium. The degranulated platelets were reaggregated by thrombin (2 U/ml). To prevent continuing effects of thrombin, FPRCH2C1 was added when thrombin-induced aggregation of thrombin-degranulated platelets reached its maximum. EDTA (5 mM) or EGTA (5 mM) added at maximum aggregation did not deaggregate these platelets, indicating that the stability of these aggregates does not depend on Ca2+ in the medium. Whereas with control platelets a combination of PGE1 (10 μM) and chymotrypsin(10 U/ml) was required for deaggregation, with thrombin-degranulated platelets either PGE1 or chymo-trypsin alone caused extensive deaggregation. The rate and extent of deaggregation of thrombin-degranulated platelets by a combination of PGE1 and chymotrypsin was greater than with control platelets.Electron microscope gold immunocytochemistry using antihuman fibrinogen IgG, anti-von Willebrand factor and anti-fibronectin showed a) that fibrinogen in the vacuoles of degranulated platelets was visible at focal points of platelet contact in the aggregates, but that large areas of platelet contact had no fibrinogen detectable between them; and b) in comparison to fibrinogen, little fibronectin or von Willebrand factor (vWf) was detectable in the platelets.Since the linkages between thrombin-degranulated platelets reaggregated by thrombin can be disrupted either by raising cAMP (thus making glycoprotein IIb/IIIa unavailable) or by proteolysis, these linkages are less stable than those formed between normal platelets. It might therefore be expected that platelets that take part in thrombus formation and then recirculate are likely to form less stable thrombi than platelets that have not released their granule contents.

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.

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 The Role of Human Platelet Preparation for Toll-Like Receptors 2 and 4 Related Platelet Responsiveness

TH Open ◽  
2019 ◽  
Vol 03 (02) ◽  
pp. e94-e102 ◽  
Author(s):  
Juergen Koessler ◽  
Marius Niklaus ◽  
Katja Weber ◽  
Angela Koessler ◽  
Sabine Kuhn ◽  
...  
Keyword(s):  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Toll Like Receptors ◽  
Preparation Methods ◽  
Expression Levels ◽  
Basal Expression ◽  
Healthy Donors ◽  
Light Transmission Aggregometry ◽  
Bacterial Patterns ◽  
Study Designs

Background Like immune cells, platelets express the repertoire of toll-like receptors (TLR), among them TLR2 and TLR4, which are important for the recognition of bacterial patterns. Receptor-mediated functional effects in platelets have been investigated, but reliable conclusions are tampered due to heterogeneous study designs with variable platelet preparation methods. This study compares TLR2- and TLR4-dependent platelet responsiveness in platelet-rich plasma (PRP) and in washed platelets (WPs). Material and Methods Fresh peripheral blood samples from healthy donors served for the preparation of PRP and WP. Basal and agonist-stimulated TLR2 and TLR4 expression levels were evaluated by flow cytometry. Light transmission aggregometry was used to investigate functional effects of TLR2 and TLR4 stimulation with Pam3CSK4 or LPS (lipopolysaccharides from Escherichia coli) as ligands. The capacity of chemokine release was determined by immunoassays. Results Pam3CSK4 and LPS (in combination with thrombin) were able to induce aggregation in WP, but not in PRP, with threshold concentrations of 15 µg/mL. Basal expression levels of TLR2 and TLR4 were higher in WP than in PRP, increasing several-fold rapidly and persistently upon platelet activation with potent agonists. Pam3CSK4 (15 µg/mL) or LPS led to the submaximal release of RANTES, PF4, PDGF, NAP-2, and sCD40L from WP. In PRP, secretory effects are less pronounced for RANTES, PDGF, or PF4, and not detectable for NAP-2 or sCD40L. Conclusion The effects mediated by TLR2 and TLR4 stimulation are dependent on platelet preparation, an important issue for experimental designs and for manufacturing of platelet concentrates in transfusion medicine.

Standardization of Light Transmission Aggregometry for Diagnosis of Platelet Disorders: An Inter-Laboratory External Quality Assessment

2019 ◽  
Vol 119 (07) ◽  
pp. 1154-1161 ◽  
Author(s):  
Karina Althaus ◽  
Barbara Zieger ◽  
Tamam Bakchoul ◽  
Kerstin Jurk ◽  
Keyword(s):  
Platelet Function ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Reference Ranges ◽  
Technical Problems ◽  
Platelet Function Disorders ◽  
Light Transmission Aggregometry ◽  
Laboratory Survey ◽  
Definition Of

AbstractSeveral in vitro platelet function tests are available for the diagnosis of inherited platelet function disorders. Currently, the light transmission aggregometry (LTA) is recommended as one of the first-step tests. LTA is available in most specialized hemostasis laboratories. Although the LTA is accepted as a ‘gold standard’ assay for the evaluation of platelet function, its standardization in the clinical practice is still challenging. The GTH-based THROMKID-Plus Study Group has performed an inter-laboratory trial in Germany and Austria. Five different agonists were selected according to the Scientific and Standardization Committee/International Society on Thrombosis and Haemostasis recommendations and shipped in 3 different sets (one should represent a healthy control and two should simulate platelet function disorders) to 15 specialized laboratories in Germany and Austria. Agonists were analyzed by APACT or PAP4/8 aggregometer using platelet-rich plasma from healthy donors. In addition, laboratory-internal platelet agonists were tested in platelet-rich plasma from a healthy donor. All laboratories (9 used APACT, 6 used PAP4/PAP8) showed very consistent data regarding the maximum percentage of aggregation induced by the tested agonists and identified the differential diagnosis of the simulated platelet function disorders with one exception, which was due to technical problems. In contrast, there was a high variability of the laboratory-internal inductors regarding reagent type, concentrations and pathological cut-off values. Our study showed that the shipment of agonists is suitable for an inter-laboratory survey of LTA. However, there is still a remarkable need for standardization of agonist reagents and their concentration as well as for definition of reference ranges.

Essential Thrombocythemia Patients with CALR Mutations Have Increased Platelet Activation Markers Compared to JAK2V617F Mutated Patients

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3223-3223
Author(s):  
Maya Koren-Michowitz ◽  
Hagit Hauschner ◽  
Yulia Shuly ◽  
Meital Nagar ◽  
Elena Ribakovsky ◽  
...  
Keyword(s):  
Essential Thrombocythemia ◽  
Conflicts Of Interest ◽  
Thrombus Formation ◽  
Absolute Number ◽  
Median Number ◽  
Healthy Controls ◽  
Activation Markers ◽  
Increased Risk ◽  
Platelet Aggregates ◽  
Calr Mutations

Abstract Essential thrombocythemia (ET) is associated with an increased risk for thrombo-hemorrhagic complications. The presence of the JAK2V617F mutation, found in approximately 50% of ET patients, has been associated with increased indices of platelet (PLT) activation suggesting its casual role in thrombus formation. Mutations in CALR were recently described in the majority of JAK2V617F negative ET patients, and are associated with a decreased rate of thrombotic events. This has led us to hypothesize that CALR mutations have a different influence on PLT activation compared to JAK2V617F. To evaluate the PLT activation state, surface expression of two PLT activation markers - p-selectin (CD62P) and PAC1 was studied using specific antibodies. MFI was analyzed by flow cytometry at baseline, as well as following ADP addition to PLT rich plasma. Monocyte-platelet aggregates were studied in whole blood samples by gating CD45+/CD14+ cells and calculating the percentage of CD41+ cells in the monocytes population. The immature PLT fraction (IPF) was analyzed with the XE-5000 hematology analyzer (Sysmex UK Ltd., Milton Keynes, UK), and the absolute number of immature PLT (nIP) was calculated from the total PLT count. Low risk ET patients (N-13, M/F-5/8) and healthy controls (N-10, M/F-4/6) are included in this analysis. JAK2V617F and CALR mutations were present in 8 and 5 patients, respectively; low dose aspirin (range 75-100mg) was taken by 85% of patients and 90% of controls. Median PLT count in CALR mutated, JAK2V617F mutated and healthy subjects was 913, 579 and 247 K/uL, respectively (p=0.0002), and it was higher in CALR compared to JAK2V617F positive patients (p=0.09). Both patient subgroups had a lower baseline MFI of p-selectin and PAC1 compared to healthy controls (p-selectin: 2.8, 3 and 4.5 for JAK2V617F [p=0.01], CALR [p=0.05] and controls; PAC1: 3, 3.3 and 5.2 for JAK2V617F [p=0.01], CALR [p=0.02] and controls, respectively) with no difference between CALR and JAK2V617F mutated patients. CALR compared to JAK2V617F mutated patients had higher median number of immature PLT (30 and 10.6 K/uL, p=0.04), and a higher fraction of monocyte- platelet aggregates (90 and 58%, p=0.05). nIP and monocyte- platelet aggregates were also significantly higher in CALR mutated but not in JAK2V617F mutated patients compared to healthy controls. Interestingly, there was no difference in post ADP PLT activation (post/baseline ratio) between ET patients and healthy controls. Finally, there were correlations between the PLT counts and nIP (R=0.8, p<0.0001), monocyte- platelet aggregates (R=0.5, p=0.02), baseline p-selectin MFI (R=-0.5, p=0.02) and PAC1 MFI (R=-0.5, p=0.01). Our preliminary results suggest a correlation between PLT activation markers and the PLT numbers, which can explain why CALR mutated patients in our cohort had higher nIP and monocyte- platelet aggregates fractions. The absence of an increased ADP induced PLT activation between patients and controls in this cohort compared with previous reports could be explained by the use of aspirin in the majority of patients and the high ADP concentration used for PLT activation. These results will be further studied in a lager cohort of patients. Disclosures No relevant conflicts of interest to declare.

Assessment of ADP-induced platelet aggregation with light transmission aggregometry and multiple electrode platelet aggregometry before and after clopidogrel treatment

2008 ◽  
Vol 99 (01) ◽  
pp. 121-126 ◽  
Author(s):  
Siegmund Braun ◽  
Stefan Jawansky ◽  
Wolfgang Vogt ◽  
Julinda Mehilli ◽  
Albert Schömig ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Whole Blood ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Platelet Aggregometry ◽  
Light Transmission Aggregometry ◽  
Before And After ◽  
Standardized Method ◽  
Multiple Electrode

SummaryThe level of platelet aggregation, measured with light transmission aggregometry (LTA) in platelet rich plasma (PRP), has been shown to predict outcomes after percutaneous coronary intervention (PCI). However, measuring parameters of platelet function with LTA is time consuming and weakly standardized. Thus, a fast and standardized method to assess platelet function after clopidogrel treatment would be of great value for clinical practice. A new method, multiple electrode platelet aggregometry (MEA), to rapidly measure platelet aggregation in whole blood has recently been developed. The aim of this study was to assess parameters of platelet function with MEA and LTA before and after administration of 600 mg clopidogrel. Blood samples from 149 patients scheduled for coronary angiography were taken after clopidogrel treatment; in addition, in 60 of the patients samples were available before clopidogrel treatment. ADP-induced platelet aggregation was measured with LTA and simultaneously in whole blood with MEA on the Multiplate analyzer. Platelet aggregation measured with MEA decreased significantly after clopidogrel treatment (P<0.0001). ADP-induced platelet aggregation assessed with MEA and LTA correlated significantly (Spearman rank correlation coefficient=0.71; P<0.0001).The results of MEA, a fast and standardized method to assess the platelet response to ADP prior to and after clopidogrel treatment, correlate well with LTA.

Evaluation of Residual Platelet Reactivity in Patients Treated with Aspirin and or Clopidogrel: Comparison of Results Obtained On Multiplate®, PFA-100TM and Classical Light Transmission Aggregometry.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3129-3129
Author(s):  
Annick Ankri ◽  
Isabelle Martin-Toutain ◽  
Anne Baranger ◽  
Marie-Claude Couty ◽  
Jean Philippe Collet ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Light Transmission ◽  
Platelet Reactivity ◽  
Biological Activities ◽  
Impedance Aggregometry ◽  
Increased Risk ◽  
Light Transmission Aggregometry ◽  
Group A ◽  
Platelet Functions ◽  
Good Agreement

Abstract Abstract 3129 Poster Board III-66 Residual platelet reactivity (RPR), despite antiplatelet therapy (AT), is currently associated with an increased risk of recurrent ischemic events and is linked to a biological resistance to AT. We determined whether whole blood impedance aggregometry using the Multiplate® (Dynabyte and IL France) detects the effects of AT as reliably as does classical light transmission aggregometry (LTA) (PAP-8, Biodis). We compared also results with those obtained on PFA-100TM (Siemens). Patients and Methods Ninety-three controls, healthy volunteers or patients without intake of AT or other drugs or pathology impairing platelet functions and 182 consecutive patients on AT were studied. Among patients, 61 received Aspirin 100mg (group A), 36 Clopidogrel 75mg (group C) and 85 the association of the two drugs. Among these 85 patients, 58 received continuously Aspirin 75mg and Clopidogrel 75mg (group AC) and 27 received a loading dose for both drugs before coronarography (group LAC). Venous blood samples were obtained on Becton Dickinson vacutainer containing citrate 0.129M. Multiplate® measures change in electrical resistance as arbitrary aggregation units (AU) over time. Aggregation is quantified as AU and area under the curve (AUC) of AU.min. On LTA, aggregation was quantified according to manufacturer's recommendations as AUC. “Resistance” to Aspirin or Aspirin RPR was determined on Multiplate® (M) using arachidonic acid at 0.5 mM (ASPITEST), in LTA with arachidonic acid at 1 mM (AA-LTA) and on PFA-100TM using the cartridge with membrane coated with epinephrine (PFA-EPI). In the same way, “resistance” to Clopidogrel was determined on M using ADP at 6.4 μM (ADPTEST), in LTA with the presence of ADP at 10 μM (ADP-LTA) and occlusion time on PFA-100TM using cartridge with membrane coated with ADP (PFA-ADP). Results All patients were tested on M, 169 on PFA-100TM and 37 with LTA. Significant correlations (p<.0001) were observed between ASPITEST and AA-LTA (r = .771), ASPITEST and PFA-EPI (r = -.42), AA-LTA and PFA-EPI (r = -.47), ADPTEST and ADP-LTA (r = .6) ADPTEST and PFA-ADP (r = -.39) and ADP-LTA and PFA-ADP (r = -.56). To define RPR on M and LTA, cut-off values (5th percentile) were determined from controls for each inducer. Treated patients presenting reactivity higher than the threshold value were considered as ‘resistant’. For PFA-100TM, results of patients under cut-off point defined by the manufacturer were considered as ‘resistant’. The frequency of “resistant” patients according to the different platelet functions tests was: a) for Aspirin: 10% on M, 4.5% with LTA and 32.8% with PFA-EPI. b) for Clopidogrel 23.1% on M 16.1% with LTA and 54.5% with PFA-ADP. A good agreement was found between ASPITEST and AA-LTA and between ADPTEST and ADP-LTA (respectively 92% and 88.7%). On the other hand, results on comparison between ASPITEST and PFA-EPI and LTA and PFA-EPI were respectively 70% and 72.6%. Results for ADPTEST and PFA-ADP were 69% and 72.3% for ADP-LTA and PFA-ADP. A significant gradation of mean AUC was observed using ASPITEST on M between all groups of subjects: controls (mean = 494±176); group A (mean = 214±186); group C (mean = 310±198); group AC (mean = 118±109); group LAC (mean = 74±45). Similar results are obtained with LTA and on PFA-100TM (except for the group C, Clopidogrel alone). Thus, a potentiating effect of Aspirin by the association with Clopidogrel may be postulated in this study. Using ADPTEST to assess the treatment response by clopidogrel, mean AUC were significantly lower for all group of patients with Clopidogrel than for controls. No gradient has been observed. Mean AUC of patients with Aspirin alone was similar to controls. In conclusion, our results confirm that Multiplate® is more effective than PFA-100TM in monitoring patients on AT. The good agreement between Multiplate® and LTA could lead to use the Multiplate® in first intention to detect RPR in these patients. Furthermore the easiness of Multiplate® use may contribute to development of new studies on biological activities of AT. Disclosures No relevant conflicts of interest to declare.

Differential effects of dialysis and ultrafiltrate from individuals with CKD, with or without diabetes, on platelet phosphatidylserine externalization

2008 ◽  
Vol 294 (1) ◽  
pp. F220-F228 ◽  
Author(s):  
Yingjie Wang ◽  
Werner Beck ◽  
Reinhold Deppisch ◽  
Sally M. Marshall ◽  
Nicholas A. Hoenich ◽  
...  
Keyword(s):  
Cardiovascular Events ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Annexin V ◽  
Uremic Toxins ◽  
Additional Increase ◽  
Phosphatidylserine Externalization ◽  
Increased Risk ◽  
Small Subpopulation ◽  
Protein Kinase Cδ

Individuals with chronic kidney disease (CKD) and/or diabetes mellitus (DM) are at increased risk of cardiovascular events and have elevated externalization of phosphatidylserine (PS; which propagates thrombus formation) in a small subpopulation of platelets. The purpose of this study was to examine the effect of 1) removing uremic toxins by hemodialysis on PS externalization in patients with either CKD or CKD and DM and 2) ultrafiltrate (UF) from these individuals on PS externalization in healthy platelets. PS externalization was quantified by a fluorescence-activated cell sorter using annexin V in platelet-rich plasma. PS externalization was elevated threefold in CKD patients and returned to basal values during 3-h hemodialysis. In contrast, it was elevated fivefold in individuals with CKD and DM and was still threefold above control after 3-h treatment. UF significantly increased PS externalization in a small subpopulation of platelets from healthy controls. The effect of UF from individuals with CKD and DM was significantly greater than that from patients with CKD alone, and the responses were partially inhibited by the protein kinase Cδ (PKCδ) inhibitor rottlerin and the 5-hydroxytryptamine (5-HT)2A/2Creceptor antagonist ritanserin. The data suggest that uremic toxins present in UF mediate PS externalization in a small subpopulation of platelets, at least in part, via the 5-HT2A/2Creceptor and PKCδ and demonstrate that DM further enhances platelet PS externalization in CKD patients undergoing hemodialysis. This may explain, at least in part, the additional increase in vascular damage observed in CKD patients when DM is present.

Platelet Aggregation Induced By Formaldehyde

1981 ◽  
Author(s):  
J A Zeller ◽  
K Eurenius ◽  
R E Dayhoff ◽  
R S Ledley ◽  
L S Rotolo
Keyword(s):  
Platelet Aggregation ◽  
Small Volume ◽  
Light Transmission ◽  
Platelet Rich Plasma ◽  
Microscopic Analysis ◽  
Formaldehyde Concentration ◽  
Microscopic Method ◽  
Light Transmission Aggregometry ◽  
Quantitative Image ◽  
Aggregation Analysis

Formaldehyde causes platelet aggregation (or agglutination) which varies with dosage. Aggregation was studied in ten blood samples drawn from normal volunteers. A small volume of formaldehyde was added to platelet rich plasma in a light transmission aggregcmeter to produce final formaldehyde concentrations between 0.1% and 8%. Measurements were made by three methods: (1) light transmission aggregometry, (2) visual semi-quantitative microscopic analysis, and (3) quantitative image analysis (Computerized Platelet Aggregation Analysis) . Using the visual semi-quantitative microscopic method, the dose response curve (expressed as the percentage of platelets involved in aggregates) increased from 11% at a formaldehyde concentration of 0.1% to 41% at a 0.5% formaldehyde concentration; it then decreased to 11% at a formaldehyde concentration of 8%. This curve may reflect the influence of two different formaldehyde effects: an aggregating effect which increases until about 0.5% concentration, whereafter a fixative effect may predominate. Light transmission aggregometry recordings did not provide a reliable indicator of the presence and degree of aggregation. A comparison of the visual semi-quantitative method and CPAA show similar detection of aggregating effects. In sunmary, formaldehyde has an aggregating effect on normal platelets. The physiologic significance of this effect is unknown; however, because formaldehyde is used to process platelets in studies of platelet aggregation, this effect may be of importance.

Sign in / Sign up

Export Citation Format

Share Document