Biomedical subjects
Publications and source records attributed to R Grewe.
In the EU more than 70 % of national law has already been replaced by EU law. Medical doctors are mostly not informed, how these EU-laws will pass. Many directives, regulations and decisions are important for medical doctors. A characterization of the EU- institutions is represented.
It was investigated whether the NO-donor SIN-1, the active metabolite of molsidomine, influenced the activation of platelets, the formation of circulating platelet aggregates, the spontaneous aggregation of platelets and the activation of the clotting system triggered by a body foreign surface in an in vitro closed-loop perfusion model. With human platelet-rich plasma at micromolar concentrations SIN-1 exerted pronounced effects on the interaction between platelets and an exogenous surface. In the absence of SIN-1, the number of circulating single platelets decreased significantly, which could be due either to the formation of circulating platelet aggregates or to the adhesion of platelets to the stent. Both these processes were blocked by the addition of SIN-1. Moreover, the platelets exhibited hyperaggregability in the absence of SIN-1 whereas the NO-donor was able to completely inhibit spontaneous platelet aggregation. Similar results were obtained in flow cytometry experiments. Without SIN-1, high platelet surface densities of both the GPIb/IX and GPIIb/IIIa receptors were observed. In addition, the density of the fibrinogen receptor increased significantly with the number of perfusion cycles. SIN-1 was able to suppress the augmented GPIIb/IIIa receptor expression significantly. Molsidomine seemed to have the potential to reduce the incidence of thrombotic processes triggered by the exogenous surface of the stent.
The modality and duration of anticoagulation before, during, and after cardioversion of atrial fibrillation--either with or without guidance by transesophageal echocardiography (TEE)--is still an unresolved issue. Intravenous infusion of unfractionated heparin until effective anticoagulation with phenprocoumon or warfarin is used as the standard therapy. However, this approach may be associated with several days of hospitalization because of the necessity for intravenous heparin administration. Moreover, there may be an increased risk of bleeding complications or, conversely, episodes of undercoagulation. Low-molecular weight heparin is an attractive alternative as it not only provide a safe and predictable level of anticoagulation with fewer side effects but can also be administered safely on an outpatient basis. In addition, no anticoagulation monitoring is needed. The ACE study (Anticoagulation in Cardioversion using Enoxaparin) is a randomized, prospective, open-label multicenter trial comparing the safety and efficacy of subcutaneous enoxaparin with intravenous heparin/oral phenprocoumon before and after cardioversion (stratified to TEE guidance or no TEE guidance). This article presents the rationale, design and status of the ACE study.
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The purpose of this review paper is to describe the various mechanisms that may lead to a decrease in the effectiveness of drugs during long-term treatment (the so-called "tolerance" or "escape phenomenon"). In addition, some precise recommendations will be made. Tolerance may be due either to degradation of the active substance by enzyme induction, as is the case e.g. with barbiturates (pharmacokinetic drug tolerance) or to down-regulation of receptors (e.g. beta-adrenergic drugs and opiates) or exhaustion of the metabolic pathways involved in pharmacological activation, as with nitrates and other drugs (pharmacodynamic drug tolerance). Whatever its mechanism, tolerance can be prevented by intermittent drug administration despite the problems inherent in the therapeutic gaps thus created. Another, more rational approach is to replace the drug concerned by a more appropriate drug which permits, or induces the restoration of receptor density when their number is reduced by the physiopathological situation (e.g. H2 stimulation instead of beta-adrenergic stimulation) or which reproduces the action of first physiological messengers, such as the endothelium-derived relaxing factor (EDRF), without requiring metabolic activation (e.g. SIN-1 or molsidomine instead of nitrates).
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We compared the effects of various nitrates, sodium nitroprusside (SNP), molsidomine, and its bioactive metabolite SIN-1, on platelet aggregation and on the activity of soluble guanylate-cyclase from human platelets. SIN-1 and SNP proved to be potent inhibitors of platelet aggregation and activated soluble guanylate-cyclase in contrast to nitrates and molsidomine which produced weak inhibition of aggregation and failed to activate soluble guanylate-cyclase. These results suggest a correlation between these products' inhibitory effect on aggregation and activation of guanylate-cyclase.
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Glaucoma has been known in medicine since Antiquity. Hippokrates described "glaykoseis" as blindness which occurs in the elderly. The English ophthalmologist Banister was the first to establish the connection between increased tension of the eyeball and glaucoma. The important invention of the ophthalmoscope by von Helmholtz (1850) made it possible to diagnose glaucomatous changes in the fundus. In 1862, Donders discovered that high intraocular pressure caused blindness and called the disease "Glaukoma simplex." Further progress in the diagnosis of glaucoma was made by the invention of the tonometer and the perimeter, and the use of cocain. The first effective surgical treatment of glaucoma, an iridectomy, was carried out by von Graefe in 1856. Drug treatment started in 1875 with the discovery of pilocarpine.
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