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  • Chemistry  (1)
  • cytochrome P 450  (1)
  • ritanserin  (1)
  • 1
    ISSN: 1432-1041
    Keywords: ritanserin ; hypertension ; serotonin ; (5 HT) ; blood pressure ; platelet aggregation ; QT interval
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have given the selective 5 HT2 antagonist ritanserin in a dose of 10 mg twice daily for 4 weeks in a double-blind, randomized, placebocontrolled, parallel group study of 18 patients with untreated essential hypertension. The fall in single platelet count due to 5 HT-induced platelet aggregation was significantly reduced by ritanserin compared with placebo (p〈0.05). There were no significant changes in supine or erect blood pressure or heart rate after ritanserin compared to placebo. Forearm blood flow, measured by mercury-in-strain gauge venous occlusion plethysmography, was not significantly altered by ritanserin. Ritanserin caused prolongation of the QTc interval by 41 (SEM 11) ms (p〈0.05 compared to placebo) but had no detectable effect on QRS duration, features suggestive of Class III antiarrhythmic activity. These findings do not support an independent role of the 5 HT2 receptor in maintaining raised arterial pressure in essential hypertension.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: stanozolol ; porphyria ; aplastic anaemia ; anabolic steroids ; haem biosynthesis ; monooxygenases ; cytochrome P 450 ; vascular thrombosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Stanozolol is an anabolic steroid which is used in the treatment of aplastic anaemia and has been recently advocated for the prophylaxis of vascular thrombosis. Similar steroid substances stimulate the activity of δ-aminolaevulinic acid synthase (ALA S), the rate limiting enzyme of haem biosynthesis, in rat hepatocytes and chick embryo liver cell cultures and activate acute hepatic porphyria. In the present study stanozolol (10 mg daily for 14 days) has been shown to increase significantly leucocyte ALA S activity in 9 healthy male subjects. There was a concomitant rise in urinary ALA and total porphyrin excretion but no change in antipyrine kinetics or urinary 6 B hydroxycortisol excretion. In a complementary study in male Sprague Dawley rats, stanozolol administered intraperitoneally, produced a dose-dependent increase in hepatic ALA S activity without changing hepatic cytochrome P 450 content. Stanozolol has been clearly shown to elevate ALA S activity, probably directly, and, thereby, porphyrin production without affecting hepatic monooxygenase activity. This porphyrinogenic effect may be relevant to the successful treatment of aplastic anaemia with anabolic steroids. Leucocyte ALA S activity may provide a human system for the study of drug porphyrinogenicity in vivo.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We investigated hemodialysis membrane biocompatibility with respect to contact phase activation by determination of FXII-like activity (FXIIA) on the membrane surface and in the supernatant phase, during plasma contact with various hemodialysis membranes using an in vitro incubation test cell. The results were compared to the influence of these membranes on the activation of purified FXII. A time course for the generation of activated FXII using purified FXII solution at physiologic concentrations on two similar negatively charged polymers was performed. The membranes assessed were regenerated cellulose (Cuprophan; Akzo Faser AG, Germany), modified cellulosic (Hemophan; Akzo Faser AG), acrylonitrile-sodium methallyl copolymer-based membrane AN69S (Hospal, France), and SPAN, a new polyacrylonitrile-based copolymer (Akzo Nobel AG). The plasma FXIIA at the membranes surface was significantly different between the membranes, while the supernatant phase FXIIA exhibited no significant differences. In contrast, activation of purified FXII in a plasma-free system with respect to supernatant activity indicated significant differences between the materials. A similar finding for the membrane-bound factor XIIA was also observed when purified factor XII was used. The membrane-bound FXIIA values observed in the plasma system containing heparin were significantly greater than in citrated plasma. This demonstrated the strong influence of heparin and the interaction of other plasma components to the membrane surface on the activation of contact phase of coagulation. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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