Search results for "platelets"

In-vitro and Ex-vivo Inhibition of Blood Platelet Aggregation by Naftazone

1996

Abstract Because of the considerable interest in the role of platelets and antiplatelet therapy in cardiovascular disease, including the aggregation of platelets to each other during arterial thrombosis and atherogenesis, we have studied the effect of naftazone (Etioven), an original vasculotropic drug on platelet aggregation. Rat and human platelets were prepared and incubated in-vitro with different concentrations of naftazone. We found that naftazone inhibited both platelet secretion and aggregation in platelet-rich plasma (PRP) and washed platelets after stimulation with thrombin or ADP. Rats were also treated intraperitoneally for five days with various naftazone doses (0.125-10 mg kg−…

Cortisol, Platelet Serotonin Content, and Platelet Activity in Patients With Major Depression and Type 2 Diabetes

2015

OBJECTIVE Hypothalamic-pituitary-adrenal system dysfunction, serotonergic system alterations, and enhanced platelet activity may contribute to the increased cardiac risk in depression. This exploratory study examined associations between cortisol parameters, platelet serotonin (5-HT) content, and platelet activity markers in patients with newly diagnosed major depression (MD) and/or Type 2 diabetes (T2DM) compared with healthy controls. METHODS We compared cortisol awakening response (CAR), diurnal decrease in salivary cortisol concentrations (slope), platelet 5-HT, and platelet markers (CD40, CD40 ligand [CD40L], soluble CD40L, CD62P, β-thromboglobulin, and platelet factor-4) in 22 T2DM pa…

Analysis and comparison of autologous platelet-rich plasma preparation systems used in the treatment of enthesopathies: A preliminary study

2021

Background Autologous platelet-rich plasma (PRP) injection is an alternative but widely accepted method for the treatment of degenerative changes in tendon attachments known as enthesopathies. The PRP is considered a safe source for high concentrations of the growth factors involved in the healing process. Despite initial promising outcomes, many recent studies report conflicting results for this treatment. This may be due to differences in the concentrations of platelets and growth factors in PRPs obtained using different methods. Objectives The aim of this study was to compare PRP preparation systems in terms of morphotic components and selected growth factors to find the most appropriate…

Clonidine increases membrane-associated phospholipase A2

2005

Background and objective: An anti-inflammatory effect of α 2 -adrenoreceptor agonists has been suggested. Phospholipase A 2 is a key enzyme in the production of precursors of inflammatory lipid mediators. The aim of the present study was to investigate the effect of clonidine on phospholipase A 2 activity in an established in vitro model. Methods: Human being platelet membranes containing active phospholipase A 2 were exposed to buffer control or to three increasing concentrations of clonidine. Phospholipase A 2 was measured by a radioisotope technique. Results: A massive increase in phospholipase A 2 activity was measured after clonidine exposure leading to final values of 92.5 ′ 3.1 pmol …

The mechanisms of thrombotic risk induced by hormone replacement therapy.

2001

Abstract Objective : To review the available information on the action of hormones on the mechanisms involved in thrombotic risk. Results and Conclusions : Thrombosis plays a crucial role in the genesis and progression of both coronary heart disease (CHD) and venous thromboembolic disease (VTED), the two main forms of cardiovascular disease. Two main determinants of the thromboembolic phenotype, hypercoagulable state and altered endothelium, accumulate much of the work performed on the influence of hormones on thrombosis. Information has accumulated mainly for oestrogens, but increasing evidences support a role for progestogens. The sensitivity of each of the three components of the hemosta…

PHOSPHODIESTERASE INHIBITORS PIROXIMONE AND ENOXIMONE INHIBIT PLATELET AGGREGATION IN VIVO AND IN VITRO

1997

The phosphodiesterase type III inhibitors piroximone (PIR) and enoximone (ENO) exert positive inotropic and vasodilating effects in patients with severe heart failure. PIR and ENO raise cyclic AMP levels in cardiac and vascular smooth muscle cells. Platelet activity is also regulated by intracellular levels of cyclic AMP. In this study we have investigated the effects of PIR and ENO on platelet activity in vivo and in vitro. PIR and ENO inhibited ADP induced platelet aggregation in a time- and concentration-dependent manner with IC50-values of 67 +/- 14 mumol/l and 129 +/- 6 mumol/l, respectively. Coincubation of PIR with the adenylate cyclase activator iloprost resulted in a synergistic po…

Platelet-endothelial interaction in tumor angiogenesis and microcirculation

2003

Activated platelets release angiogenic growth factors and have therefore been proposed to contribute to tumor angiogenesis within a potentially prothrombotic tumor microcirculation. The aim of the study was to investigate interactions of platelets with the angiogenic microvascular endothelium of highly vascularized solid tumors during growth and in response to endothelial stimulation in comparison with normal subcutaneous tissue. Experiments were performed in the dorsal skinfold chamber preparation of C57BL/6J mice bearing the Lewis lung carcinoma (LLC-1) or methylcholanthrene-induced fibrosarcoma (BFS-1). Fluorescently labeled rolling and adherent platelets, red blood cell velocity, and ve…

Amyloid precursor protein in platelets of patients with Alzheimer disease: effect of acetylcholinesterase inhibitor treatment.

2001

BACKGROUND:Amyloid precursor protein (APP) forms with apparent molecular weights of 130, 110, and 106 kd are present in human platelets. It has been demonstrated that Alzheimer disease (AD) is specifically associated with a decreased APP forms ratio in platelets. OBJECTIVE:To investigate whether acetylcholinesterase (AChE) inhibitor treatment modifies the ratio of platelet APP forms in patients with AD. PATIENTS AND METHODS:From a large sample of patients with probable AD, 30 with mild to moderate AD were selected. Each patient underwent a clinical evaluation including the Mini-Mental State Examination (MMSE) and platelet APP forms analysis at baseline and after 30 days. During this interva…

Thrombocytopenia Associated With Levodopa Treatment

2003

Membrane fluidity, membrane lipid pattern, and cytosolic Ca2+ content in platelets from a group of type II diabetic patients with macrovascular compl…

1995

OBJECTIVE To evaluate platelet membrane fluidity and some platelet metabolic parameters in type II diabetic patients with macrovascular complications. RESEARCH DESIGN AND METHODS In a group of 21 type II diabetic patients with macrovascular complications, we evaluated platelet membrane fluidity [marking intact resting platelets with the fluorescent probe 1,4-(trimethylamino)-phenyl-4-phenylhexatriene (TMA-DPH)], platelet membrane lipid pattern (cholesterol :phospholipid [C:PL] ratio and individual phospholipids), and platelet cytosolic Ca2+ content (marking intact resting platelets with the fluorescent probe Fura 2AM). RESULTS Platelet membrane fluidity is decreased in type II diabetic pat…