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Tuula Syngelmä

Other affiliations: University of Eastern Finland
Bio: Tuula Syngelmä is an academic researcher from University of Oulu. The author has contributed to research in topics: Microsome & Biological activity. The author has an hindex of 3, co-authored 3 publications receiving 239 citations. Previous affiliations of Tuula Syngelmä include University of Eastern Finland.

Papers
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Journal ArticleDOI
TL;DR: The data suggest that despite slightly differing molecular masses, the human and mouse P-450s supporting COH are structurally conserved at their active centers.

124 citations

Journal ArticleDOI
TL;DR: The results suggest that the coumarin-type compounds in particular interact with the active sites of Cyp2a-5 and CYP2A6, and the active Sites are structurally different, since a number of compounds inhibited mouse, but not human COH activity.

93 citations

Journal ArticleDOI
TL;DR: The present results indicate that the human 15 alpha OH is different from the mouse P45015 alpha, and metyrapone clearly inhibited COH in mouse liver microsomes, but interestingly it had no effect on COH activity in human liver microSomes, although these two isozymes have been shown to be immunologically similar.

26 citations


Cited by
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Journal ArticleDOI
TL;DR: A status report summarizing their reactions, substrates, Inducers, and Inhibitors is given in this article, with a focus on human CYtochrome P450 enzymes.
Abstract: (1997). Human Cytochrome P450 Enzymes: A Status Report Summarizing Their Reactions, Substrates, Inducers, and Inhibitors. Drug Metabolism Reviews: Vol. 29, No. 1-2, pp. 413-580.

1,170 citations

Journal ArticleDOI
TL;DR: The purpose of this review is to compare and contrast the human P 450s involved in drug metabolism with their related forms in the rat and other experimental species with respect to their relative levels of the various P450s and their metabolic capabilities.
Abstract: The cytochromes P450 are a superfamily of hemoproteins that catalyze the metabolism of a large number of xenobiotics and endobiotics. The type and amount (i.e., the animal's phenotype) of the P450s expressed by the animal, primarily in the liver, thus determine the metabolic response of the animal to a chemical challenge. A majority of the characterized P450s involved in hepatic drug metabolism have been identified in experimental animals. However, recently at least 12 human drug-metabolizing P450s have been characterized at the molecular and/or enzyme level. The characterization of these P450s has made it possible to "phenotype" microsomal samples with respect to their relative levels of the various P450s and their metabolic capabilities. The purpose of this review is to compare and contrast the human P450s involved in drug metabolism with their related forms in the rat and other experimental species.

945 citations

Journal ArticleDOI
TL;DR: This chapter is an update of the data on substrates, reactions, inducers, and inhibitors of human CYP enzymes published previously by Rendic and DiCarlo, now covering selection of the literature through 2001 in the reference section.
Abstract: This chapter is an update of the data on substrates, reactions, inducers, and inhibitors of human CYP enzymes published previously by Rendic and DiCarlo (1), now covering selection of the literature through 2001 in the reference section. The data are presented in a tabular form (Table 1) to provide a framework for predicting and interpreting the new P450 metabolic data. The data are formatted in an Excel format as most suitable for off-line searching and management of the Web-database. The data are presented as stated by the author(s) and in the case when several references are cited the data are presented according to the latest published information. The searchable database is available either as an Excel file (for information contact the author), or as a Web-searchable database (Human P450 Metabolism Database, www.gentest.com) enabling the readers easy and quick approach to the latest updates on human CYP metabolic reactions.

788 citations

Journal ArticleDOI
01 Jan 2005-Drugs
TL;DR: An extensive review of the literature identified reported herb-drug interactions with clinical significance, although the underlying mechanisms for the altered drug effects and/or concentrations by concomitant herbal medicines are yet to be determined.
Abstract: Herbs are often administered in combination with therapeutic drugs, raising the potential of herb-drug interactions. An extensive review of the literature identified reported herb-drug interactions with clinical significance, many of which are from case reports and limited clinical observations. Cases have been published reporting enhanced anticoagulation and bleeding when patients on long-term warfarin therapy also took Salvia miltiorrhiza (danshen). Allium sativum (garlic) decreased the area under the plasma concentration-time curve (AUC) and maximum plasma concentration of saquinavir, but not ritonavir and paracetamol (acetaminophen), in volunteers. A. sativum increased the clotting time and international normalised ratio of warfarin and caused hypoglycaemia when taken with chlorpropamide. Ginkgo biloba (ginkgo) caused bleeding when combined with warfarin or aspirin (acetylsalicylic acid), raised blood pressure when combined with a thiazide diuretic and even caused coma when combined with trazodone in patients. Panax ginseng (ginseng) reduced the blood concentrations of alcohol (ethanol) and warfarin, and induced mania when used concomitantly with phenelzine, but ginseng increased the efficacy of influenza vaccination. Scutellaria baicalensis (huangqin) ameliorated irinotecan-induced gastrointestinal toxicity in cancer patients. Piper methysticum (kava) increased the ‘off’ periods in patients with parkinsonism taking levodopa and induced a semicomatose state when given concomitantly with alprazolam. Kava enhanced the hypnotic effect of alcohol in mice, but this was not observed in humans. Silybum marianum (milk thistle) decreased the trough concentrations of indinavir in humans. Piperine from black (Piper nigrum Linn) and long (P. longum Linn) peppers increased the AUC of phenytoin, propranolol and theophylline in healthy volunteers and plasma concentrations of rifamipicin (rifampin) in patients with pulmonary tuberculosis. Eleutheroccus senticosus (Siberian ginseng) increased the serum concentration of digoxin, but did not alter the pharmacokinetics of dextromethorphan and alprazolam in humans. Hypericum perforatum (hypericum; St John’s wort) decreased the blood concentrations of ciclosporin (cyclosporin), midazolam, tacrolimus, amitriptyline, digoxin, indinavir, warfarin, phenprocoumon and theophylline, but did not alter the pharmacokinetics of carbamazepine, pravastatin, mycophenolate mofetil and dextromethorphan. Cases have been reported where decreased ciclosporin concentrations led to organ rejection. Hypericum also caused breakthrough bleeding and unplanned pregnancies when used concomitantly with oral contraceptives. It also caused serotonin syndrome when used in combination with selective serotonin reuptake inhibitors (e.g. sertraline and paroxetine). In conclusion, interactions between herbal medicines and prescribed drugs can occur and may lead to serious clinical consequences. There are other theoretical interactions indicated by preclinical data. Both pharmacokinetic and/or pharmacodynamic mechanisms have been considered to play a role in these interactions, although the underlying mechanisms for the altered drug effects and/or concentrations by concomitant herbal medicines are yet to be determined. The clinical importance of herb-drug interactions depends on many factors associated with the particular herb, drug and patient. Herbs should be appropriately labeled to alert consumers to potential interactions when concomitantly used with drugs, and to recommend a consultation with their general practitioners and other medical carers.

557 citations

Journal ArticleDOI
TL;DR: The mechanism of cou marin-induced tumour formation in rodents is associated with metabolism-mediated, toxicity and it is concluded that exposure to coumarin from food and/or cosmetic products poses no health risk to humans.

462 citations