Platelet Aggregation In Diabetic Patients Research Articles

Rac1 Modulates Endothelial Function and Platelet Aggregation in Diabetes Mellitus.

BackgroundVascular complications and abnormal platelet function contribute to morbidity and mortality in diabetes mellitus. We hypothesized that the Rho‐related GTPase protein, Rac1, can influence both endothelial and platelet function and might represent a potential novel therapeutic target in diabetes mellitus.Methods and ResultsWe used both in vitro and ex vivo approaches to test the effects of pharmacological inhibition of Rac1 during hyperglycemic condition. We evaluated the effect of NSC23766, a pharmacological inhibitor of Rac1, on vascular function in diabetic mice and platelet aggregation in diabetic subjects. We demonstrated that the administration of NSC23766 protects from hyperglycemia‐induced endothelial dysfunction, restoring NO levels, and reduces oxidative stress generated by nicotinamide adenine dinucleotide phosphate oxidase. Mechanistically, we identified Rho‐associated coiled‐coil serine/threonine kinase‐1 as a downstream target of Rac1. Moreover, we reported that during hyperglycemic conditions, human platelets showed hyperactivation of Rac1 and impaired NO release, which were both partially restored after NSC23766 treatment. Finally, we characterized the antiplatelet effect of NSC23766 during hyperglycemic conditions, demonstrating the additional role of Rac1 inhibition in reducing platelet aggregation in diabetic patients treated with common antiplatelet drugs.ConclusionsOur data suggest that the pharmacological inhibition of Rac1 could represent a novel therapeutic strategy to reduce endothelial dysfunction and platelet hyperaggregation in diabetes mellitus.

Effect of a 180 mg ticagrelor loading dose on myocardial necrosis in patients undergoing elective percutaneous coronary intervention: A preliminary study.

To examine whether a loading dose of ticagrelor on top of clopidogrel reduced postpercutaneous coronary intervention (PCI) myonecrosis. Seventy seven coronary artery disease patients received a loading dose of 300 mg clopidogrel pre-PCI and were divided into three groups: group TT (n = 36): a loading dose of 180 mg ticagrelor pre-PCI, followed by ticagrelor 90 mg twice daily commencing one day post-PCI; group CT (n = 26): a maintenance dose of ticagrelor 90 mg twice daily; group CC (n = 15): clopidogrel 75 mg daily post- PCI. High sensitivity cardiac troponin T (hs-cTnT) and creatine kinase-MB (CK-MB) were measured pre-PCI and 0 h, 2 h or 24 h post-PCI. Platelet aggregation was measured in a separate cohort of 54 coronary artery disease patients (35 diabetic and 19 non-diabetic patients). There were no significant differences in hs-cTnT and CK-MB concentration among the three groups. In group TT, diabetic patients had significant higher Δhs-cTnT2h-0h than non-diabetic patients. In the second cohort, although baseline platelet aggregation was higher in diabetic than non-diabetic patients, platelet aggregation was comparable between diabetic and non-diabetic patients at 0 and 2 h post-PCI. This study indicates that a loading dose of ticagrelor does not significantly reduce post- PCI myonecrosis. Diabetes is associated with more post-PCI myonecrosis. A loading dose of ticagrelor effectively reduces platelet aggregation in diabetic patients.

English

This study examined the effects of anthropometric variables and metabolic imbalance on platelet aggregation in diabetic patients. A total of 109 volunteer were used; 58 diabetes mellitus (DM) patients (28 males and 30 females) who were receiving treatment at the University College Hospital Ibadan and 51 non diabetic control recruited from residents of Agbowo and Teachers of some secondary schools within the University of Ibadan. Body mass index (BMI)  and body surface area (BSA) were assessed as indices of anthropometry, fasting blood sugar (FBS), plasma cholesterol and triglycerides (TAG)  were determined using standard method and platelet aggregation test was done on the whole blood. Platelet aggregation ratio was higher in non diabetic compared to the diabetic subjects (P<0.001). The mean platelet aggregation ratio was also significantly higher in the male diabetic when compared to the female diabetic group (P<0.001). There was a significant linear relationship between platelet aggregation ratio and BMI (P<0.01), age (P0.05), FBS (P< 0.01), plasma cholesterol (P<0.01) and plasma TAG (P<0.05). However, the correlation coefficient between platelet aggregation ratio and BSA is not significant. In the non diabetic control subjects the correlation coefficient is not significant. Findings from this study suggest that, the increased platelet aggregation found in diabetic patients increased significantly with increased BMI but decrease with age. The mean platelet aggregation is also increased significantly with increase metabolic imbalance.   Key word: Platelet aggregation, anthropometry, diabetes mellitus, Body mass index (BMI), fasting blood sugar (FBS).

Diurnal variation in platelet inhibition by clopidogrel

Morning increase in the occurrence of myocardial infarction, stroke and sudden cardiac death is a well-recognized phenomenon, which is in line with a morning enhancement of platelet aggregation. We investigated whether platelet inhibition during clopidogrel and aspirin therapy varies during the day. Fifty-nine consecutive patients (45 men and 14 women) with first ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary interventions (pPCI) on dual antiplatelet therapy were prospectively enrolled into the study. Blood samples were collected 4 days after start of clopidogrel treatment at 6.00 a.m., 10.00 a.m., 2.00 p.m. and 7.00 p.m. Arachidonic acid and adenosine diphosphate (ADP)-induced platelet aggregation were assessed by impedance aggregometry. Platelet inhibition by clopidogrel was lowest in the midmorning: median ADP-induced platelet aggregation was 55%, 17% and 27% higher at 10.00 a.m. compared to 6.00 a.m., 2.00 p.m. and 7.00 p.m., respectively (p < 0.002). Nonresponsiveness to clopidogrel defined according to the device manufacturer was 2.4-fold more frequent in the midmorning than in the early morning. We observed a more pronounced midmorning increase in ADP-induced platelet aggregation in diabetic patients when compared to non-diabetics. In contrast, no diurnal variation in the antiplatelet effect of aspirin was observed. In conclusion, in patients presenting with STEMI undergoing pPCI, platelet inhibition by clopidogrel is less strong in the midmorning hours. This periodicity in platelet aggregation in patients on dual antiplatelet therapy should be taken into consideration when assessing platelet function in clinical studies.

Validity of particle‐counting method using laser‐light scattering for detecting platelet aggregation in diabetic patients

AbstractWe aimed to study the validity of a new analytical approach that reflected the phase from platelet activation to the formation of small platelet aggregates. We hoped that this new approach would enable us to use the particle‐counting method with laser‐light scattering to measure platelet aggregation in healthy controls and in diabetic patients without complications. We measured agonist‐induced platelet aggregation for 10 min. Agonist was added to the platelet‐rich plasma 1 min after measurement started. We compared the total scattered light intensity from small aggregates over a 10‐min period (established analytical approach) and at over a 2‐min period from 1 to 3 min after measurement started (new analytical approach). We found that platelet aggregation in diabetics with HbAlc ≥ 6.5% was significantly greater than in healthy controls by both analytical approaches. However, platelet aggregation in diabetics with HbAlc &lt; 6.5%—patients in the early stages of diabetes—was significantly greater than in healthy controls only by the new analytical approach, not by the established analytical approach. These results suggest that platelet aggregation as detected by the particle‐counting method using laser‐light scattering could be applied in clinical examinations by our new analytical approach. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(3): 1–8, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10057

Validity of Particle-Counting Method Using Laser-Light Scattering for Detecting Platelet Aggregation in Diabetic Patients

We aimed to study the validity of a new analytical approach that reflected the phase from platelet activation to the formation of small platelet aggregates. We hoped that this new approach would enable us to use the particle-counting method with laser-light scattering to measure platelet aggregation in healthy controls and in diabetic patients without complications. We measured agonist-induced platelet aggregation for 10 min. Agonist was added to the platelet-rich plasma 1 min after measurement started. We compared the total scattered light intensity from small aggregates over a 10-min period (established analytical approach) and that over a 2-min period from 1 to 3 min after measurement started (new analytical approach). Consequently platelet aggregation in diabetics with HbA1c ≥ 6.5% was significantly greater than in healthy controls by both analytical approaches. However, platelet aggregation in diabetics with HbA1c < 6.5%, i.e. patients in the early stages of diabetes, was significantly greater than in healthy controls only by the new analytical approach, not by the established analytical approach. These results suggest that platelet aggregation as detected by the particle-counting method using laser-light scattering could be applied in clinical examinations by our new analytical approach.

Increased platelet aggregation in diabetic patients with microangiopathy despite good glycemic control

The pathogenesis of diabetic micro- and macroangiopathy cannot be fully explained by hyperglycemia alone. To clarify diabetic complications mediated by increased platelet activity, we have studied platelet aggregation and its second messenger molecules such as protein kinase C (PKC), RhoA, and phosphatidylinositol 3-kinase (PI3- kinase), in six diabetic patients with diabetic retinopathy and other diabetic complications in spite of good glycemic control. Their HbA 1c levels throughout the observation period had been less than 6% with diet treatment alone, despite which diabetic retinopathy developed to the pre-proliferative stage during 2-8 years observation. Low-dose thrombin (< 0.5 U/ml)-stimulated platelet aggregation in the diabetic patients was enormously elevated compared with healthy control subjects. PKC, RhoA and PI3-kinase activities in the cytosol- and membrane-associated fractions were examined in the platelets from the two patients (Cases 2 and 4). Platelet membrane-associated RhoA and PI3-kinase activity in Case 2 were increased before the stimulation. Platelet RhoA and PI 3-kinase activities in Case 4 were increased after the stimulation with low-dose thrombin (0.01 U/ml). Membrane-associated immunoreactive PKC f , but not PKC g in Cases 2 and 4 was elevated. Although platelet hyperactivity in these four patients was observed, PKC and RhoA in mononuclear leukocytes from these patients were not different from healthy subjects. Membrane-associated PKC f and RhoA immunoreactivities also increased in the other three cases. These results suggest that hyperreactivity of PKC f may lead to increased RhoA and PI3-kinase activities and platelet hyperfunction in diabetic patients with good glycemic control, and that raised platelet PKC f may be implicated in the pathogenesis of diabetic complications.

Platelet protein kinase C isoform content in type 2 diabetes complicated with retinopathy and nephropathy

It has been reported that platelet aggregation in diabetic patients with microangiopathy is increased compared with healthy subjects. Chronic hyperglycemia is known to cause an increase in diacylglycerol level in various tissues. We examine whether protein kinase C (PKC) isoform content in platelets from diabetic patients is increased compared with healthy subjects, as previously described in the retina, aorta, and heart of diabetic rats. Platelet PKC α , β and ζ immunoreactivity in cytosol, membrane and cytoskeleton (CS) fractions were analyzed by immunoblotting in 20 type 2 diabetic patients (who had been treated with diet alone, sulphonylureas or insulin, and whose condition was complicated with retinopathy, nephropathy, neuropathy and/or macroangiopathy) and in five healthy subjects. PKC α , β and ζ immunoreactivity in cytosol, membrane and CS fractions in platelets from diabetic subjects were not significantly higher than those from healthy subjects. However, platelet PKC β immunoreactivity in cytosol fraction was significantly higher in diabetic patients with normal serum creatinine (Cr) level than in diabetic patients with abnormal Cr level (Cr S 1.5 mg/dl) or in healthy subjects. Moreover, significant negative correlation between PKC β immunoreactivity in cytosol fraction of platelets and serum Cr level was found in diabetic patients ( P < 0.05). To clarify the effect of treatment for diabetes, PKC isoform immunoreactivity in platelets was measured in type 2 diabetic patients treated with diet alone, sulphonylurea or insulin treatment. Serum creatinine level in diabetic patients with insulin treatment was significantly higher than in diabetic patients with sulphonylurea treatment and diet alone. In addition, PKC β immunoreactivity in diabetic patients with insulin treatment was significantly suppressed compared with that in patients treated by sulphonylurea treatment. These results suggest that chronic hyperglycemia may activate platelet PKC β isoform, and that insulin treatment may decrease platelet PKCβactivity. Finally, not only PKC β antagonists, but also glycemic control by insulin may prevent development of diabetic microangiopathy.

Plasma and platelet taurine are reduced in subjects with insulin-dependent diabetes mellitus: effects of taurine supplementation

Plasma and platelet taurine concentrations were assayed in 39 patients with insulin-dependent diabetes mellitus (IDDM) and in 34 control subjects matched for age, sex, and both total and protein-derived daily energy intake. Platelet aggregation induced by arachidonic acid in vitro at baseline and after oral taurine supplementation (1.5 g/d) for 90 d was also studied. Plasma and platelet taurine concentrations (mean +/- SEM) were lower in diabetic patients (65.6 +/- 3.1 mumol/L, or 0.66 +/- 0.07 mol/g protein) than in control subjects (93.3 +/- 6.3 mumol/L, or 0.99 +/- 0.16 mol/g protein, P < 0.01). After oral supplementation, both plasma and platelet taurine concentrations increased significantly in the diabetic patients, reaching the mean values of healthy control subjects. The effective dose (mean +/- SEM) of arachidonic acid required for platelets to aggregate was significantly lower in diabetic patients than in control subjects (0.44 +/- 0.07 mmol compared with 0.77 +/- 0.02 mmol, P < 0.001, whereas after taurine supplementation it equaled the mean value for healthy control subjects (0.72 +/- 0.04 mmol). In in vitro experiments, taurine reduced platelet aggregation in diabetic patients in a dose-dependent manner, whereas 10 mmol taurine/L did not modify aggregation in healthy subjects.

Plasma and platelet taurine are reduced in subjects with insulin-dependent diabetes mellitus: effects of taurine supplementation.

Plasma and platelet taurine concentrations were assayed in 39 patients with insulin-dependent diabetes mellitus (IDDM) and in 34 control subjects matched for age, sex, and both total and protein-derived daily energy intake. Platelet aggregation induced by arachidonic acid in vitro at baseline and after oral taurine supplementation (1.5 g/d) for 90 d was also studied. Plasma and platelet taurine concentrations (mean +/- SEM) were lower in diabetic patients (65.6 +/- 3.1 mumol/L, or 0.66 +/- 0.07 mol/g protein) than in control subjects (93.3 +/- 6.3 mumol/L, or 0.99 +/- 0.16 mol/g protein, P < 0.01). After oral supplementation, both plasma and platelet taurine concentrations increased significantly in the diabetic patients, reaching the mean values of healthy control subjects. The effective dose (mean +/- SEM) of arachidonic acid required for platelets to aggregate was significantly lower in diabetic patients than in control subjects (0.44 +/- 0.07 mmol compared with 0.77 +/- 0.02 mmol, P < 0.001, whereas after taurine supplementation it equaled the mean value for healthy control subjects (0.72 +/- 0.04 mmol). In in vitro experiments, taurine reduced platelet aggregation in diabetic patients in a dose-dependent manner, whereas 10 mmol taurine/L did not modify aggregation in healthy subjects.

Thrombin-induced platelet aggregation, phosphoinositide metabolism and protein phosphorylation in NIDDM patients treated by diet, sulphonylurea or insulin

We studied thrombin-induced metabolism of phosphoinositide, protein phosphorylation and platelet aggregation in platelets from 32 NIDDM patients and 12 control subjects. To clarify the effect of diet, sulphonylureas, or insulin treatment, the subjects were divided into three groups based on the type of treatment. Thrombin-induced platelet aggregation was measured with an aggregometer. Low-dose thrombin (0.25 U/ml)-stimulated platelet aggregation in diabetic patients was significantly increased compared with the control subjects. Platelet aggregation in the sulphonylurea and insulin groups was significantly lower than in the diet group. On the other hand, in platelets incubated with [32P]orthophosphate, thrombin-induced incorporation of 32P radioactivity into phosphatidic acid (PA) was significantly lower in the sulphonylurea and insulin groups than in the diet group. Thrombin-induced incorporation of [32P] radioactivity into phosphatidylinositol (PIP) for 10 s was significantly higher in the sulphonylurea group than in the diet group. There were no differences in thrombin-induced 47 kDa protein phosphorylation between platelets from the diet, sulphonylurea, or insulin groups. These results suggest that sulphonylureas and insulin induce suppression of thrombin-induced activation of phospholipase C, which mediates hydrolysis of PIP and PIP2 and production of PA, which leads to inhibition of platelet aggregation.

Abnormalities of Platelet Aggregation in Diabetic Patients with Symptomatic Peripheral Neuropathy

Abnormalities of Platelet Aggregation in Diabetic Patients with Symptomatic Peripheral Neuropathy

Nicomol の血清脂質ならびに血小板脂質, 容積, アデニン・ヌクレオチッド含量, 凝集能に及ぼす効果

Nicomol の血清脂質ならびに血小板脂質, 容積, アデニン・ヌクレオチッド含量, 凝集能に及ぼす効果

Platelet Factor 4 (PF4) Release during Human Platelet Aggregation in Diabetic Patients

SummaryThe release of platelet factor 4 during platelet aggregation was investigated in diabetic patients. We observed an increased release of platelet factor 4 in diabetic patients.The authors suggest that the increased release of platelet factor 4 may play an essential role in pathogenesis of thromboembolic complications in diabetes mellitus.