Pradipta Jana

Dermcidin isoform-2 induced nullification of the effect of acetyl salicylic acid in platelet aggregation in acute myocardial infarction

The aggregation of platelets on the plaque rupture site on the coronary artery is reported to cause both acute coronary syndromes (ACS) and acute myocardial infarction (AMI). While the inhibition of platelet aggregation by acetyl salicylic acid was reported to produce beneficial effects in ACS, it failed to do in AMI. The concentration of a stress induced protein (dermcidin isoform-2) was much higher in AMI than that in ACS. Incubation of normal platelet rich plasma (PRP) with dermcidin showed one high affinity (Kd = 40 nM) and one low affinity binding sites (Kd = 333 nM). When normal PRP was incubated with 0.4 μM dermcidin, the platelets became resistant to the inhibitory effect of aspirin similar to that in the case of AMI. Incubation of PRP from AMI with dermcidin antibody restored the sensitivity of the platelets to the aspirin effect. Incubation of AMI PRP pretreated with 15 μM aspirin, a stimulator of the NO synthesis, resulted in the increased production of NO in the platelets that removed the bound dermcidin by 40% from the high affinity binding sites of AMI platelets. When the same AMI PRP was retreated with 10 μM aspirin, the aggregation of platelets was completely inhibited by NO synthesis.

Reduction of death rate due to acute myocardial infarction in subjects with cancers through systemic restoration of impaired nitric oxide.

Introduction Excessive aggregation of platelets at the site of plaque rupture on the coronary artery led to the formation of thrombus which is reported to precipitate acute myocardial infarction (AMI). Nitric oxide (NO) has been reported to inhibit platelet aggregation and induce thrombolysis through the in situ formation of plasmin. As the plasma NO level in AMI patients from two different ethnic groups was reduced to 0 µM (median) compared to 4.0 µM (median) in normal controls, the effect of restoration of the NO level to normal ranges on the rate of death due to AMI was determined. Methods and Results The restoration of plasma NO level was achieved by a sticking small cotton pad (10×25 mm) containing 0.28 mmol sodium nitroprusside (SNP) in 0.9% NaCl to the abdominal skin of the participants using non-toxic adhesive tape which was reported to normalize the plasma NO level. The participants (8,283) were volunteers in an independent study who had different kinds of cancers and did not wish to use any conventional therapy for their condition but opted to receive SNP “pad” for their condition for 3 years. The use of SNP “pad” which normalized (≈4.0 µM) the plasma NO level that in consequence reduced the death rate due to AMI, among the participants, was found to be significantly reduced compared to the death due to AMI in normal population. Conclusion Our data suggested that the use of SNP “pad” significantly reduced the death due to AMI. Trial Registration www.ctri.nic.in 004236

Estriol, a stimulator of nitric oxide synthesis in platelets, and its role as the powerful inhibitor of platelet aggregation

Women, before menopause, are known to be resistant to the development of acute ischemic heart disease (AIHD). As the inhibition of platelet aggregation is reported to prevent incidences of AIHD, the effects of estradiol and estriol on ADP-induced platelet aggregation in platelet-rich plasma were determined. It was found that it was not estradiol, the most potent estrogenic hormone, but estriol, less potent than estradiol, that had a minimum inhibitory concentration (MIC) of 0.6 nmol/l for 100% inhibition of ADP-induced platelet aggregation. In contrast, the MIC of estradiol was 2.0 nmol/l (P<0.005, n=40). The stimulation of nitric oxide (NO) by 0.6 nmol/l estriol in platelet-rich plasma was 0.55 nmol/108 cells/h and the stimulation by the 2.0 nmol/l estradiol was 0.179 nmol/108 cells/h. Treatment of intact platelets with 0.05% Triton X-100 released a membrane NO synthase in the supernatant that had basal Km of 5.28 mmol/l with Vmax of 0.029 nmol NO/mg/h. The treatment of the supernatant with 0.6 nmol/l estriol decreased the Km to 3.42 mmol/l with increased Vmax to 0.337 nmol NO/mg/h. These results showed that estriol was one of the most potent inhibitors of platelet aggregation with MIC that was in subnanomolar ranges, which is lower than any other inhibitors currently known and suggested that estriol might prevent AIHD in women before menopause.

Estriol-induced fibrinolysis due to the activation of plasminogen to plasmin by nitric oxide synthesis in platelets.

Estriol, an oestrogen, at 0.6 nmol/l was reported to inhibit ADP-induced platelet aggregation through nitric oxide synthesis. As nitric oxide has been reported to cause fibrinolysis due to the activation of plasminogen to plasmin, the role of estriol as a fibrinolytic agent was investigated. Also, the mechanism of estriol-induced nitric oxide synthesis in anucleated platelets was investigated. The estriol-induced lysis of platelet-rich plasma (PRP) clot was determined by photography of the clot lysis and by the assay of fibrin degradation products in the lysate and was obtained by SDS-PAGE. Nitric oxide was determined by methemoglobin method. The platelet membrane protein was isolated from the platelets by using Triton X-100 (0.05% v/v). The binding of estriol to the protein was determined by Scatchard plot by using an ELISA for estriol. Estriol at 0.6 nmol/l was found to lyse the clotted PRP due to fibrinolysis that produced fibrin degradation products in the lysate. The amino acid analysis of the platelet membrane protein, which resembles with nitric oxide synthase (NOS) activity, was activated nearly 10-fold over the control in the presence of estriol and was identified to be a human serum albumin precursor (Mr. 69 kDa) that binds to estriol with Kd1 of 6.0 × 10−9 mol/l and 39 ± 2 molecules of estriol bound the NOS molecule. The estriol-induced nitric oxide is capable of inducing fibrinolysis of the clotted PRP. The binding of estriol to platelet membrane NOS activated the enzyme in the absence of DNA in the platelet.