On the prophylactic and therapeutic use of danaparoid sodium (Orgaran) in patients with heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a rare but dangerous complication of heparin prophylaxis or treatment. The present laboratory tests to measure heparin-associated antibodies are not specific. The diagnosis of HIT mainly depends on the decrease in platelet count and on clinical symptoms. To evaluate clinical outcome, bleeding complications and platelet counts were evaluated in 45 patients with HIT type II (HIT II) treated prophylactically (subcutaneous injections) or therapeutically (intravenous infusion) with danaparoid. Group I included 24 patients with HIT II without thromboembolic complications who received danaparoid twice daily subcutaneously (10 IU/kg) for a mean of 16 days. Group II included 21 patients with thromboembolic complications. They were treated with intravenous danaparoid (2.6 IU/kg/h +/- 1.1) for a mean of 17 days. During subcutaneous prophylaxis, mean anti-Xa levels of 0.2 U/mL and during intravenous treatment, mean anti-Xa levels of 0.4 U/mL were reached. No deaths, amputations, or serious bleeding complications occurred, and no new thromboses were observed in both patient groups. Treatment with danaparoid led to a fast normalization of the platelet counts. This normalization occurred earlier and the concentration of platelets was higher in patients treated with intravenous doses. Danaparoid with subsequent vitamin K-antagonist treatment effectively prevents thromboembolic complications in patients with HIT.

Adverse reactions to anticoagulants and to antiplatelet drugs recorded by the German spontaneous reporting system.

According to their code of professional conduct, German physicians are obliged to report suspected cases of adverse drug reactions (ADRs) to the Drug Commission of the German Medical Association (AkdA). On the basis of an agreement between the German Medical Association and the Federal Institute for Drugs and Medical Devices (BfArM) a common pharmacovigilance database within the German spontaneous reporting system was created. A user-friendly application program developed in-house enables the user to conduct searches about reported ADRs covering a wide variety of questions within a short period of time. ADRs caused by anticoagulants and by antiplatelet drugs still belong to the most reported adverse events. The most frequently reported suspected drugs are heparins, followed by ticlopidine, phenprocoumon, acetylsalicylic acid, and clopidogrel. Bleeding complications are the most often described ADR symptoms of any anticoagulation therapy, especially of phenprocoumon and acetylsalicylic acid. Another serious ADR is heparin-induced thrombocytopenia or changes in blood counts (CBC) due to ticlopidine and clopidogrel. During the past few years a reduction in severe reactions, such as cerebral hemorrhage, especially with fatal outcome was detectable because of better clinical management of oral anticoagulant therapy and of adverse events concerning heparin.

Retention test Homburg to monitor the adhesive properties of von Willebrand factor after substitution or desmopressin therapy.

To diagnose von Willebrand disease (vWD) and to monitor drug efficacy, several tests have been established that are not, however, focused on the platelet adhesion properties of von Willebrand factor (vWF). The new platelet retention test Homburg (RTH) is characterized by a nonthrombogenic filter that retains platelets from blood when it is pressed through this filter. It was the aim of this study to examine the capability of this test to monitor the adhesive properties of vWF after its substitution in vWD or its release by desmopressin infusion. The RTH demonstrated a striking sensitivity for vWF after its release from endogenous storage sites or its supplementation in vivo as well as in vitro, whereas it did not detect an inhibition of platelet aggregability due to aspirin. Desmopressin infusions led to an immediate and highly significant increase of RTH platelet retention, followed by a gradual decline to initial values during the next 4 hours. The transfusion of a vWF concentrate also resulted in RTH data that demonstrated different kinetics than established parameters such as vWF:antigen, vWF:RiCoF, or the PFA-100 in vitro bleeding analysis. Additional in vitro experiments confirmed the correlation of RTH values with vWF concentrations. In conclusion, the RTH may be efficient to complement presently used measures to monitor vWD therapy with desmopressin or vWF concentrates.

Adhesion, spreading, and aggregation of platelets in flowing blood and the reliability of the retention test Homburg.

Adhesion and aggregation are important parameters characterizing the function of intact platelets in flowing blood and in contact with a more or less thrombogenic surface. In the retention test Homburg (RTH), platelets are exposed to a standardized textured surface (Sysmex retention tubes) under defined conditions of flow. Platelet counts are performed before and after the Sysmex retention tube passage. The difference between these values indicates the percentage of retained platelets (retention index). Decreased retention in the RTH indicates a loss of function or defective platelet function; increase is associated with an increased activation of platelets, for example, in patients with vascular diseases. For further evaluation of the retention phenomenon the filters were fixed after cell passage and examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM micrographs show activated platelets adhering and spreading on the filter surface, comparable with platelets on a disturbed endothelium. Also, we examined the influence of different G forces and centrifugation times on the retention behavior of the platelets in citrated platelet-rich plasma (PRP) and whole blood (WB). G forces influenced the retention index in PRP and WB significantly and in a different way. Finally, we used a platelet standard, as customary in the quality check, to determine the serial as well as the day-to-day precision.

Role of the retention test Homburg in evaluating platelet hyperactivity and in monitoring therapy with antiplatelet drugs.

Decreased retention in the retention test Homburg (RTH) indicates a loss of platelet function; increase is associated with an increased activation of platelets, for example, in patients with vascular diseases. Compared with other materials (e.g., collagen, glass pearls, etc.) the filter surface in the retention tubes is nonthrombogenic. Therefore, the RTH seems to be well suited for measuring an in vivo over-reactivity of platelets. In a pilot study using the RTH we evaluated the postoperative over-reactivity of platelets in 14 patients and observed a significant heterogeneity of the platelet population concerning size and stickiness. Reliable platelet function tests are also necessary for "drug monitoring," since they deliver important clinical laboratory parameters for efficient control of a therapy with antiplatelet drugs. Therefore, we evaluated in vitro how, after administration of platelet aggregation-inhibiting medications (such as acetylsalicylic acid, Prostaglandin and ReoPro in various concentrations, the adenosine diphosphate (ADP), collagen, ristocetin, or suprarenin increased retention can be reduced. The reaction of the platelets in platelet-rich plasma of different patients or donors to the addition of ADP is variable. The platelet function inhibitor effect is dose dependent. In a clinical pilot study, a significant platelet-inhibiting effect of clopidogrel using the RTH has been shown.

Time-trends in the epidemiology of peptic ulcer bleeding.

OBJECTIVE: Despite the introduction of effective medical treatment of peptic ulcer disease, bleeding is still a frequent complication. The aim of this study was to investigate whether the incidence and the risk profile of peptic ulcer haemorrhage have changed within a 10-year period. MATERIAL AND METHODS: In a prospective epidemiological and observational study the incidence and risk profile of peptic ulcer haemorrhage in Düsseldorf, Germany were compared between two time periods (period A: 1.3.89-28.2.90 and period B: 1.4.99-31.3.2000), involving nine hospitals with both surgical and medical departments. Patients with proven peptic ulcer haemorrhage at endoscopy or operation were included in the study; those with bleeding under defined severe stress conditions were excluded. RESULTS: No differences in bleeding ulcer incidence were observed between periods A and B (51.4 per 100,000 person-years versus 48.7), or for duodenal ulcer (24.9 versus 25.7) or for gastric ulcer bleeding (26.5 versus 23.0). A marked increase in incidence rates was observed with increasing age. In period B, patients with bleeding ulcers were older (56% versus 41% 70 years or older), were usually taking non-steroidal anti-inflammatory drugs (NSAIDs) (45% versus 27%) and were less likely to have a history of ulcer (25% versus 59%) compared with patients in period A. CONCLUSIONS: The persisting high incidence of peptic ulcer disease is a superimposing of two trends: a higher incidence in the growing population of elderly patient with a higher intake of NSAIDs and a lower incidence among younger patients due to a decrease in incidence and improved medical treatment.

Comparative analysis of platelet isolation techniques for the in vivo study of the microcirculation.

OBJECTIVE: In vitro and in vivo studies using isolated platelets require that the cells used for testing are not activated by the isolation procedure. This ensures that the effects measured by the test are the result of the environment or the applied stimulus, but is not an artifact resulting from activation by cell isolation. METHODS: Herein, we analyzed two different platelet isolation procedures (i.e., a Sepharose column versus density gradient centrifugation) with special emphasis on cell activation, including flow cytometric analysis of P-selectin expression, functional quantification of mechanical platelet retention, light microscopic assessment of platelet aggregation, and fluorescence microscopic determination of in vivo rat liver platelet-endothelium cell interaction. RESULTS: Under resting conditions, Sepharose column-isolated platelets showed a negligible fraction of only 2.7 +/- 3.3% cells (mean +/- SEM) with P-selectin expression, and an appropriate response (i.e., a 33-fold increase) upon activation with thrombin receptor-activating peptide (TRAP). In contrast, density gradient centrifugation resulted in P-selectin expression under resting conditions of approximately 50% of the isolated cells and only a 1.6-fold increase on further TRAP stimulation. In addition, density gradient-isolated platelets, but not Sepharose column-isolated platelets, showed increased mechanical retention and agglutination/aggregation in vitro, as well as pronounced adhesion to hepatic venular endothelium in vivo. Interestingly, density gradient-isolated platelets additionally induced in vivo an increase of colocalization of platelets with adherent leukocytes, indicating a generalized microvascular inflammatory response that is comparable to that observed after a 60-minute ischemia/30-minute reperfusion insult. CONCLUSION: Density gradient centrifugation-isolated platelets, but not Sepharose column-isolated platelets, are activated already under resting conditions and induce in vivo a platelet-leukocyte-endothelial cell-associated inflammatory response. Thus, we propose that the method of platelet isolation using the Sepharose column is superior to the density gradient centrifugation technique and might therefore be preferred for in vitro and in vivo assays to study platelet function.