Thrombopoietin activates human platelets and induces tyrosine phosphorylation of p80/85 cortactin.

The mechanism of human platelet activation by thrombopoietin (TPO) was investigated in vitro. We found that rHuTPO stimulated thromboxane A2 formation and serotonin secretion, despite the absence of shape change and aggregation. Blockade of the arachidonic acid pathway did not inhibit rHuTPO-induced platelet secretion. rHuTPO stimulated the tyrosine phosphorylation of 64, 80/85, 95, 130 and 140 kDa proteins, but phosphoproteins of 100-105 and 125 kDa obtained when platelets aggregated in the presence of thrombin were absent. rHuTPO stimulated and potentiated the thrombin-induced tyrosine phosphorylation of a 80 kDa protein identified as the cortical actin-associated protein, p80/85 cortactin. When platelets were aggregated in the presence of rHuTPO and fibrinogen, cortactin phosphorylation was enhanced as compared to rHuTPO alone. Treatment with RGDS or cytochalasin D respectively reduced or abolished cortactin tyrosine phosphorylation. This confirms the existence of fibrinogen binding-dependent and independent pools of phosphorylated cortactin, both requiring intact actin polymerization. Cytoskeleton-binding proteins may be implicated in in vitro platelet activation by rHuTPO.

Sensitivity of the ProC global assay for protein C pathway abnormalities. clinical experience in 899 unselected patients with venous thromboembolism.

The ProC Global is a clotting assay designed to globally evaluate the functionality of the protein C (PC) pathway, which is found defective in up to 30% of the Caucasian patients with thrombophilia. It is based on the ability of endogenous activated protein C (APC), generated by activation of PC by a snake venom extract, to prolong an activated partial thromboplastin time (APTT). This retrospective study was carried out to evaluate the ability of this assay to distinguish patients with or without any PC pathway abnormalities in a cohort of 899 unselected patients with a history of thrombosis. The result of the ProC Global assay, expressed in PC activation time-normalized ratio (PCAT-NR), was significantly lower in patients in whom was previously demonstrated an abnormality of the PC pathway compared to those without. The cut-off level of PCAT-NR=0.75 was found to provide the best sensitivity-specificity ratio, since all the patients with the factor V (FV) Leiden mutation (n=71), APC resistance (n=3), PC deficiency (n=22), or combined defects (n=19) had a PCAT-NR below that value. The sensitivity of the ProC Global assay for a low protein S (PS) level (n=56) was only 66%, and was even weaker in the case of hereditary PS deficiency (46.6%, n=15). The assay did not perform well in samples from patients on oral anticoagulant treatment (OAT, n=64) or with liver failure (n=4), as the PCAT-NR was reduced in most cases, even in the absence of any abnormality. These results suggest that the ProC Global assay could be validly used as a first-step screening test for the FV Leiden-related APC resistance and PC deficiency in patients not on OAT. Given the moderate sensitivity of the assay for PS deficiency, this coagulation inhibitor must be determined in every case. However, the overall benefit of such a screening strategy is limited since more than 38% of the 659 patients without abnormality had a decreased PCAT-NR.

[Postdonation information: the French fourth hemovigilance sub-process]. / L'information post-don, le quatrième sous-processus de l'hémovigilance.

Postdonation information is the knowledge of information about the donor or his donation, occurring after it, which challenges quality or safety of the blood products stemming from this or other donations. Classical hemovigilance sub-processes concerning donors or recipients adverse events do not cover this topic. France is just about to make it official as a fourth sub-process. Less formal management of postdonation information is already set up for more than ten years. French data of the year 2013 are presented, including the regional notification level and the national reporting one. A significant level of heterogeneity is observed as for other hemovigilance sub-processes. It is mainly due to subjective rather than objective differences in risk appreciation. A real consensual work is expected about it in the future.

Willingness to undergo HIV testing in the Kintampo districts of Ghana.

BACKGROUND: HIV testing is currently a major prevention intervention and remains an entry point to early treatment, care and support. Uptake is however low and alternative approaches are currently being adopted. OBJECTIVE: An HIV module was incorporated into the routine survey of the Kintampo Health and Demographic Surveillance System (KHDSS) to assess the willingness of adults living in the Kintampo North and South districts to undergo HIV testing. DESIGN: The study was a descriptive cross-sectional household survey. Univariate and multivariate analysis were used to identify predictors of the willingness to undergo HIV testing. PARTICIPANTS: Respondents were community members aged 15 to 49 years and selected from randomly generated household listings from the KHDSS. RESULTS: A total of 11,604 respondents were interviewed, 10,982 (94.6%) of respondents had good general knowledge on HIV/AIDS. Among those with knowledge about HIV/AIDS, 10,819 (98.5%) indicated their willingness to get tested for HIV. Rural residents were more willing to undergo HIV testing than urban dwellers Odds ratio=1.42 (95% Confidence interval: 1.03, 1.96; P-value=0.031). Respondents with primary education were more likely to go for testing relative to those without any education OR=2.02 (95% CI: 0.87, 4.70; P-value=0.046). CONCLUSION: Expressed willingness to test for HIV is high in this population. Exploring community and population-based interventions to HIV testing and counseling could increase uptake of HIV testing services and should be considered. The underlying motivations need to be explored in order to translate willingness into actual testing.