Chronic obstructive pulmonary disease. A possible correlation between platelet aggregation tests and respiratory indexes. ECOB Group.

It has been suggested that thrombotic events occurring in patients with chronic obstructive pulmonary disease could be partially due to abnormalities in blood coagulation and fibrinolysis, as well as to changes in platelet function. In the present study in vitro platelet aggregation, in addition to clotting activity, has been studied in 20 patients with chronic obstructive pulmonary disease and different degrees of alteration of blood gas analysis. The results obtained suggest that the presence of a condition of platelet hypoaggregability characterizes patients with marked hypercapnia and/or hypoxemia, whereas the improvement of respiratory indexes is followed by a trend to normalization, or, more often, to an increase of platelet activity.

Circadian variations in platelet aggregability in non insulin dependent diabetes patients (NIDDM).

Circadian rhythms of platelet activity have been extensively investigated in recent years in view of a possible correlation with the increased morning frequency of thrombotic events. Since a role of enhanced platelet activity has been suggested in diabetic macro- and microvascular disease, the aim of the present study was to analyze the circadian variations of in vitro platelet aggregability in patients with non insulin-dependent diabetes mellitus. Eighteen in-patients, ranging in age from 49 to 73 years, all in good metabolic control, were included in the study. Aggregometric patterns were analyzed in blood samples collected at 0700, 0900, 1100 and 1700. A significant increase of the threshold concentrations for ADP-collagen- and arachidonic acid-induced platelet aggregation has been observed in the interval 0700-1100 or 0700-1700, suggesting, also in diabetic patients as in normal subjects, a maximum of platelet activity in the morning, regardless of postural changes and timing of meals.

Differential platelet proaggregating activity of three Burkitt's lymphoma-derived human cell lines.

We demonstrate a differential platelet in vitro proaggregating activity in three Burkitt's lymphoma--derived human B cell lines, i.e. Daudi, Raji and P3H-R1. Functional and ultrastructural findings indicated the ability of Daudi cells to induce a marked secondary irreversible platelet aggregation, while the Raji cells only induced a primary-type reversible platelet response; no evidence of proaggregating activity has been obtained for P3H-R1 cells. Luminometric assays indicated that contact of Daudi and Raji, but not P3H-R1, cells with platelet rich plasma (PRP) or platelet poor plasma (PPP) was followed by ADP release, in the range of 2,2-3,5 microM and 0.4-0.6 microM respectively for Daudi and Raji cells. After preincubation of PRP with apyrase Daudi cells induced a reversible platelet response similar to that obtained with the use of Raji cells: then, the irreversible complete platelet response induced by Daudi cells was to be related to ADP release from degranulating platelets. Experiments in gel-filtered platelet systems showed that the plasma co-factor inducing ADP release from Daudi and Raji cells was not fibrinogen. Specific inhibition of platelet thrombin receptors, as well as of cycloxygenase and lipoxygenase pathways, did not modify the proaggregating activity of Daudi and Raji cells. Work is in progress to characterize the plasma factor interacting with Daudi and Raji, but not P3H-R1 cells, and the differences between the three cell lines which support this differential interaction.

Blood cellular and biochemical changes after extracorporeal shock wave lithotripsy.

The present study deals with blood cell behaviour and related hematochemical changes occurring in man after exposure to extracorporeal shock wave lithotripsy (ESWL). The following parameters have been investigated, before and after treatment, in a longitudinal study carried out on 58 patients of our Center: RBC count, Ht, Blood Hb, Plasma Hb, autohemolysis after 72 hours, bilirubinemia, WBC count, platelet count, in vitro platelet aggregation, beta-TG, sideremia and urinary post-exposure transferrin concentration. After exposure to ESWL, with pulse numbers ranging from 350 to 3,000, 18-20 KV, direct and indirect evidences of hemolysis have been found when number of SW exceeded 1,000. The hemolysis rate in different models of in vitro exposure to ESWL of blood samples was also investigated. Increase of WBC count, and changes of the platelet in vitro aggregation patterns were also observed. Changes in sideremia values have been related to urinary loss of transferrin.

In vitro enhancement of human platelet aggregation by somatostatin.

Very low concentrations of somatostatin (S-14) strongly potentiate the in vitro aggregation induced by collagen, ristocetin and arachidonic acid, but not that induced by ADP or epinephrine, in both human platelet rich plasmas and gel-filtered platelet preparations. Desensitization phenomena may be induced either by repeated addition of S-14 or long lasting contact between S-14 and platelets.