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  • Halogenated monoterpenes  (2)
  • Chain models  (1)
  • 1
    ISSN: 1432-0843
    Schlagwort(e): Key words Halomon ; Natural products ; Halogenated monoterpenes ; Pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The purpose of the present study was to define the plasma pharmacokinetics, bioavailability, and tissue distribution in mice of halomon, a halogenated monoterpene from Portieria hornemanii that is active in vitro against brain-, renal-, and colon-cancer cell lines. Halomon formulated in cremophor : ethanol : 0.154 M NaCl (1 : 1 : 6, by vol.) was injected i.v. at 20, 60, 90, or 135 mg/kg into female CD2F1 mice. Doses of 135 mg/kg were also given i.p., s.c., and by enteral gavage to female CD2F1 mice and i.v. to male CD2F1 mice. Plasma halomon concentrations were measured with a gas-chromatography system using electron-capture detection. Halomon concentrations were also determined in the brains, hearts, lungs, livers, kidneys, spleens, skeletal muscles, fat, red blood cells, and, if present, testes of mice given 135 mg/kg i.v. Halomon plasma pharmacokinetics were well fit by a two-compartment, open linear model and were linear between 20 and 135 mg/kg. Population estimates of parameters describing halomon plasma pharmacokinetics in female CD2F1 mice were developed with a standard two-stage technique and also by simultaneous modeling of data from 20-, 60-, 90-, and 135-mg/kg i.v. studies in female mice. Halomon bioavailability was 45%, 47%, and 4% after i.p., s.c., and enteral dosing, respectively. Urinary excretion of the parent compound was minimal. Halomon was distributed widely to all tissues studied but was concentrated and persisted in fat. Halomon concentrations measured in the brain were comparable with concomitant concentrations detected in plasma and most other tissues. These data and models are helpful in the simulation and evaluation of conditions produced by preclinical screening and toxicology studies.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0843
    Schlagwort(e): Key words Halomon ; Natural products ; Halogenated monoterpenes ; Cytochrome P450
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objectives: To characterize the enzymes responsible for and metabolites produced from the metabolism of halomon, a halogenated monoterpene that is isolated from the red algae Portieria hornemanii and has in vitro activity in the NCI screen against brain, renal, and colon cancer cell lines. Materials and methods: Mouse and human liver fractions, prepared by homogenization and differential centrifugation, were incubated with halomon, extracted with toluene, and analyzed by gas chromatography. Results: In the presence of NADPH, mouse-liver 9,000-g supernatant (S9) fractions metabolized halomon, but boiled S9 fractions did not. NADH could not substitute for NADPH. Further separation of murine hepatic S9 fractions produced a microsomal fraction that contained all of the halomon-metabolizing activity; cytosol had none. Carbon monoxide reduced murine hepatic microsomal metabolism of halomon, whereas an anaerobic, N2 environment greatly accelerated the disappearance of halomon. Human hepatic microsomes metabolized halomon and required NADPH to do so. Carbon monoxide completely inhibited human hepatic microsomal metabolism of halomon. Unlike murine hepatic microsomal metabolism of halomon, anaerobic conditions did not enhance the metabolism of halomon by human hepatic microsomes. Neither 100 μM diethyldithiocarbamate, 1 μM quinidine, 100 μM ciprofloxacin, 3 μM ketoconazole, nor 100 μM sulfinpyrazone inhibited the metabolism of halomon by human hepatic microsomes. Both murine and human hepatic microsomes produced a metabolite of halomon. The mass spectrum of this metabolite indicated the loss of one chlorine atom and one bromine atom. Conclusions: Halomon is metabolized by mouse and human hepatic cytochrome P-450 enzymes, the identities of which remain unknown. Hepatic metabolism of halomon is very consistent with the concentrations of halomon measured in mouse tissues and urine after i.v. administration of the drug.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Research in engineering design 8 (1996), S. 81-98 
    ISSN: 1435-6066
    Schlagwort(e): Chain models ; Design for manufacture ; Design theory ; Solid modeling ; Topology ; Tolerance Modeling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Technik allgemein
    Notizen: Abstract Aspects of the mathematical specialty of topology appear within several seemingly distinct areas of engineering design and engineering design theory. Indeed, the expression “topology of a design” is often used informally. In this article a primary intent is to demonstrate the diversity of applications of topology within engineering design. A complementary goal is to introduce the engineering design community to topology as a rich, formal, well-established mathematical discipline that may be of value for wider study. Upon reviewing some of these topological applications, it appears that topology holds promise as a basis for formalizing engineering design theory. This article considers topology as a basis for unifying design abstractions. The potential benefit may be the realization of commonalities between design aspects previously considered separately, where each now has its own attendant specialized, expensive analyses.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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