Antagonism of P2Y12 reduces physiological thromboxane levels.

Antiplatelet therapy for the management of patients with cardiovascular risks often includes a combination therapy of aspirin and clopidogrel, acting through inhibition of thromboxane generation and blockade of G(i)-coupled P2Y12 receptor, respectively. We hypothesized that ADP acting through P2Y12 regulates physiological thromboxane levels. The serum thromboxane levels in mice (n = 3) dosed with clopidogrel and prasugrel were decreased by 83.1 ± 5.3% and 94.26 ± 1.75% respectively compared to untreated mice. Pre-treatment of human blood (n = 3) ex vivo with active metabolites of clopidogrel or prasugrel led to a reduction in thromboxane levels to 16.3 ± 3.2% and 4.9 ± 0.8% respectively, compared to untreated human serum. We also evaluated serum thromboxane levels in P2Y receptor null mice (n = 4). Whereas serum thromboxane levels in P2Y1 null mice were similar to those in wild type littermates, those in the P2Y12 null mice were inhibited by 83.15 ± 3.8%. Finally, in a pilot study, serum thromboxane levels were reduced by 76.05 ± 8.41% in healthy human volunteers (n = 6) upon dosing with clopidogrel, compared to the levels before dosing. In conclusion, P2Y12 antagonism alone can decrease physiological thromboxane levels. Thus, this study could pave way the for newer/modified treatment regimens for the management of patients with thrombotic complications who are allergic or non-responsive to aspirin.

Complex atrial septal defect: percutaneous repair guided by three-dimensional echocardiography.

Three-dimensional transesophageal echocardiography (3D TEE) has been used to guide the percutaneous repair of simple atrial septal defects (ASDs). There has been limited experience in using this imaging modality to guide complex ASD repair. In this report, we describe how 3D TEE was used to guide the repair of a complex, multifenestrated ASD. In a single view, 3D TEE provides a superior anatomic definition when compared to the traditional two-dimensional echocardiography. We believe that this emerging technology will play a critical role as the number and complexity of percutaneous techniques treating structural heart disease continue to rise. (Echocardiography 2010;27:590-593).

Risk of thrombogenicity among nonionic radiocontrast agents.

Several contrast agents have been approved in the United States for radiographic imaging purposes. Most of the older ionic, high-osmolar contrast agents are no longer used because of their side effect profile. Therefore, newer nonionic, low or iso-osmolar contrast agents have been widely accepted as an alternative due to their improved tolerability and safety. We investigated the thrombogenicity of the 6 different nonionic radiocontrast media in terms of their platelet reactivity and noted some minor differences among them. In the 50% contrast concentration group, all of the nonionic contrast agents inhibited aggregation, whereas in the 10% contrast concentration group, all agents showed similar aggregation curves in comparison to the normal control. At 50% contrast concentration, the inhibitory effect of aggregation appeared to be related to the inhibition of calcium mobilization, which may be one of the mechanistic effects.

Carotid artery in-stent restenosis after carotid artery stenting.

Carotid in-stent restenosis is a potential long-term sequela that may occur after carotid artery stenting. We report a single-center experience with this procedure and reviewed the database for individual patient characteristics and possible management options.

Scleromyxedema.

Scleromyxedema is a rare cutaneous mucinous disease characterized by a generalized papular sclerodermoid eruption and systemic manifestations that can lead to significant morbidity and mortality. Although its etiology remains unknown, most theories focus on a pathogenic role by paraproteins; it must be noted, however, that nonparaprotein factors have been suggested to cause fibroblast proliferation and increased mucin production. Several treatment modalities including melphalan, cyclophosphamide, interferon alfa, and plasmapheresis have been suggested; however, further research is needed to prove treatment efficacy.

CD11c gene expression in hairy cell leukemia is dependent upon activation of the proto-oncogenes ras and junD.

Hairy cell leukemia (HCL) is a chronic lymphoproliferative disease, the cause of which is unknown. Diagnostic of HCL is abnormal expression of the gene that encodes the beta2 integrin CD11c. In order to determine the cause of CD11c gene expression in HCL the CD11c gene promoter was characterized. Transfection of the CD11c promoter linked to a luciferase reporter gene indicated that it is sufficient to direct expression in hairy cells. Mutation analysis demonstrated that of predominant importance to the activity of the CD11c promoter is its interaction with the activator protein-1 (AP-1) family of transcription factors. Comparison of nuclear extracts prepared from hairy cells with those prepared from other cell types indicated that hairy cells exhibit abnormal constitutive expression of an AP-1 complex containing JunD. Functional inhibition of AP-1 expressed by hairy cells reduced CD11c promoter activity by 80%. Inhibition of Ras, which represents an upstream activator of AP-1, also significantly inhibited the CD11c promoter. Furthermore, in the hairy cell line EH, inhibition of Ras signaling through mitogen-activated protein kinase/extracellular signal-regulated kinase kinases 1 and 2 (MEK1/2) reduced not only CD11c promoter activity but also reduced both CD11c surface expression and proliferation. Expression in nonhairy cells of a dominant-positive Ras mutant activated the CD11c promoter to levels equivalent to those in hairy cells. Together, these data indicate that the abnormal expression of the CD11c gene characteristic of HCL is dependent upon activation of the proto-oncogenes ras and junD.