Failure of the platelet-activating-factor antagonist WEB 2086 BS for treatment of chronic autoimmune thrombocytopenia.

Thirteen patients with chronic autoimmune thrombocytopenia (AITP) were treated for 14 days with daily oral doses of 120 mg of the novel platelet-activating-factor (PAF) antagonist WEB 2086 BS. Clinical bleeding symptoms remained essentially unchanged in 9 patients and became more pronounced in the post-treatment period in 4 patients. In no case was an increase in platelet counts observed. While the PAF antagonist was well tolerated subjectively during treatment, most patients exhibited a prolongation of the sensitive "hemostasis time" (a modified bleeding time test) after treatment, but the Duke bleeding time was not changed. We conclude that the PAF antagonist WEB 2086 BS is ineffective for treatment of chronic AITP and should be used with caution in thrombocytopenic patients.

"Haemostasis time", a modified bleeding time test and its comparison with the Duke and Ivy/template bleeding times. II. Application in bleeding disorders.

"Haemostasis time" (HT), the occlusion time of a Butterfly 25 short cannula inserted into the cubital vein, is a bleeding time modification comparable to the skin bleeding times according to Duke and Ivy/Mielke. It also measures platelet function and is not influenced more than the latter tests by clotting factors. In HT, subendothelium is replaced by a standard artificial surface. The technique was investigated in patients with haemophilia A and B, von Willebrand's disease (vWD), and defects of factors VII and XI. HT was prolonged in 9/16 patients with haemophilia A/B, but did not correlate with the factor VIII:C/IX:C values. However, it reflected the different bleeding tendencies in those patients as represented by early or late onset of bleeding symptoms and occurrence of spontaneous haemarthroses. Of the vWD patients, not classified by multimeric analysis, 15/31 had prolonged Simplate II bleeding times, 14/31 prolonged HTs. Only 20/31 patients had corresponding normal or prolonged bleeding times with both techniques. HT correlated significantly with the Duke bleeding time (p = 0.011), ristocetin cofactor activity (p = 0.003) and von Willebrand factor antigen (p = 0.022), while no correlations were found between these parameters and the Simplate II method. Statistical evaluation shows, that in vWD, HT can replace the less precise Duke bleeding time but not the non-related Ivy/Simplate techniques.

Morphology of the interaction of collagen fibrils with normal human platelets and thrombasthenic platelets.

The ultrastructure of the platelet contacts with collagen fibrils (CF) as well as the course taken by CF on the platelet surface were studied on ultrathin sections of platelets and CF. Platelets from normal donors and from a patient with thrombasthenia were incubated in citrated plasma with collagen. For electron microscopy a protein-stabilizing fixation procedure was applied. Platelet-collagen contacts (PCC) are characterized by a distance of 7 +/- 3 nm between the platelet membrane and the CF; the gap contains electron-dense bridges. The PCC of normal and thrombasthenic platelets are morphologically identical. Hence, it is unlikely that the glycoproteins IIb/IIIa-complex, which is absent in thrombasthenic platelets, plays a significant role in the platelet collagen interaction. The CF induce random movements of the platelets and their pseudopods, whereby the fibrils, which often show multisite attachment, coil up around the platelet surface; they become bent and often display drastic directional changes. CF are found inside invaginations of the platelet membrane as well as in depressions of the platelet surface. These processes require an involvement of the platelet's contractile system, which appears to interact reversibly with the platelet plasma membrane.

"Haemostasis time", a modified bleeding time test and its comparison with the Duke and Ivy/template bleeding times. I. Normal values, application in thrombocytopenic patients and evaluation of heparin and aspirin effects.

The occlusion time ("haemostasis time" - HT) of a thin, short cannula inserted into the cubital vein, was compared with the skin bleeding times of the Duke and Ivy/template techniques. 25 male and 25 female volunteers without a history of bleeding were divided into 5 equally large age groups ranging from 10 to over 50 years of age. They exhibited a range of 46 s-6 min 38 s (95% tolerance interval), while the Duke and Ivy/template bleeding times, which were simultaneously determined, corresponded to values given by other authors. HT is different from the skin bleeding times in that endothelium is replaced by a standard foreign surface which allows better standardization of the method. Similar results were obtained with HT compared to the skin bleeding times. These and a similar, non-significant heparin response with all three techniques suggest that HT is not more influenced by clotting factors than the Duke and Ivy/template bleeding times and, indeed, may be regarded as a bleeding time modification. HT, like both of the skin bleeding times, reflected lowered platelet counts and is even more sensitive in this respect. As tested in a group of 20 male and 20 female volunteers, HT showed a significant prolongation two hours after ingestion of 1 g aspirin. While male individuals exhibited longer bleeding times than females with the Ivy/template technique (sex-related difference p = 0.01), no male to female differences were found both with HT and the Duke bleeding time. HT is easy to perform, inexpensive, leaves no scars and is safe even for the patient with severe bleeding. Moreover, compared to the skin bleeding times, it permits a differential evaluation of vessel wall and tissue effects.

Pancreatic endocrine carcinoma with ectopic PTH-production and paraneoplastic hypercalcaemia.

In a case of pancreatic endocrine carcinoma hypercalcaemia without bone metastases and normal parathyroid glands prompted our suspicion that there was paraneoplastic production of an osteoclast activating substance by the tumour tissue. This view was further confirmed by bone histology. Immunohistology post mortem revealed the production of PTH in the primary tumour and a liver metastasis. The usefulness of immunohistology in detecting paraneoplastic secretion of hormonal substances is discussed.

Nucleated thrombocytoid cells. II. Phase- and interference-contrast microscopic studies on blood cells of the domestic fowl.

The so-called nucleated thrombocytes of the domestic fowl (and mallard) were analyzed intravitally by use of phase- and interference-contrast microscopy with regard to their morphology and functional state, and in comparison to other avian blood cells and mammalian blood platelets. Since nucleated thrombocytoid cells of birds do not differ in size from white blood cells, they are automatically included in differential cell counts. They can easily be confused with other white blood cells and even with erythrocyte ghosts, which also appear to be hemostatically active elements. However, the nucleated thrombocytoid cells displayed a characteristic, definite morphology. The platelet-like spreading process and elongation of aging cells in vitro to spindle forms deserve special attention. A technique of counting live avian blood cells was used to determine their values in chickens of different sexes and ages.

The nucleated thrombocytoid cells. I. Electron microscopic studies on chicken blood cells.

By analyses of electron micrographs it was investigated whether nucleated thrombocytes of chickens described in the literature can be differentiated from lymphoid cells with sufficient certainty as an independent cell system. The result was negative. The mixture of lymphoid cells and so-called thrombocytes investigated was extremely polymorphous and, unlike mammalian platelets, proved to be one cell system containing younger and more mature cells. In the literature cells with signs of overmaturity or activation are designated as thrombocytes. Our studies suggest that a genuine thrombocyte system of chickens and other birds is not existent. The cell hitherto considered as nucleated thrombocytes seem to belong to the lymphoid system.