Idiopathic and secondary osteonecrosis of the femoral head show different thrombophilic changes and normal or higher levels of platelet growth factors.

BACKGROUND AND PURPOSE: Thrombophilia represents a risk factor both for idiopathic and secondary osteonecrosis (ON). We evaluated whether clotting changes in idiopathic ON were different from corticosteroid-associated ON. As platelet-rich plasma has been proposed as an adjuvant in surgery, we also assessed whether platelet and serum growth factors were similar to those in healthy subjects. METHODS: 18 patients with idiopathic ON and 18 with corticosteroid-associated ON were compared with 44 controls for acquired and inherited thrombophilia. Platelet factor 4 (PF4), transforming growth factor-ß1, platelet-derived growth factor-BB (PDGF-BB), and vascular endothelial growth factor were assayed in the supernatants of thrombin-activated platelets, in platelet lysates, and in serum from 14 ON patients and 10 controls. RESULTS: Idiopathic ON patients had higher plasminogen levels (median 118%) than controls (101%) (p = 0.02). Those with corticosteroid-associated ON had significantly higher D-dimer (333 ng/mL) and lower protein C levels (129%) than controls (164 ng/mL, p = 0.004; 160%, p = 0.02). The frequency of inherited thrombophilia was not different from the controls. No statistically significant differences were found between idiopathic and corticosteroid-associated ON. 20 of the 36 ON patients were smokers. (The controls were selected from smokers because nicotine favors hypercoagulability). ON patients had significantly higher serum PF4 levels (7,383 IU/mL) and PDGF-BB levels (3.1 ng/mL) than controls (4,697 IU/mL, p = 0.005; 2.2 ng/mL, p = 0.02). INTERPRETATION: Acquired hypercoagulability was common in both ON types, but the specific changes varied. The release of GF from platelets was not affected, providing a biological basis for platelet-rich plasma being used as an adjuvant in surgical treatment.

A study of leucocyte removal by the RemoweLL cardiotomy reservoir.

BACKGROUND: Cerebral damage is a relatively frequent complication of cardiopulmonary perfusion. Leucocyte activation and lipid microembolisation are among the possible causes. The removal of leucocytes and lipid microparticles from the cardiotomy suction blood could prevent this complication. METHODS: We studied the properties of a cardiotomy reservoir (RemoweLL, EUROSETS), which contains a filtering layer designed to remove some leucocytes and lipid microparticles. The reservoir was loaded with red cell concentrates or whole blood units, some of them containing hyperlipidaemic plasma. The extent of leucocyte and lipid removal was evaluated with reference to the storage age and pre-filtration absolute values of the products. RESULTS: On average, the cardiotomy reservoir removed 35-39% of total leucocytes, with a slight preference for neutrophil granulocytes. This device also retained 26-30% of platelets. The efficiency was not influenced by the storage age of the filtered product nor by the total cell load, within the explored range (323x10(6) - 1,345 x10(6) total leucocytes). Lipid (cholesterol, triglycerides) removal was minimal (about 3-6%). DISCUSSION: The RemoweLL device removed more than a third of the leucocytes from the processed blood. Lipid removal was minimal but the lipid particles in our model (chylomicrons) have a diameter 100-fold smaller than the particles believed to be responsible for clinical effects. This device seems promising and worthy of further studies to document the saturation point of leucocyte removal. On the other hand, lipid removal should be studied in a model more closely resembling the clinical situation in which the device is expected to be used.