Endogenous neurosteroids and their synthetic analogues-neuroactive steroids-have been found to bind to muscarinic acetylcholine receptors and allosterically modulate acetylcholine binding and function. Using radioligand binding experiments we investigated their binding mode. We show that neuroactive steroids bind to two binding sites on muscarinic receptors. Their affinity for the high-affinity binding site is about 100 nM. Their affinity for the low-affinity binding site is about 10 µM. The high-affinity binding occurs at the same site as binding of steroid-based WIN-compounds that is different from the common allosteric binding site for alcuronium or gallamine that is located between the second and third extracellular loop of the receptor. This binding site is also different from the allosteric binding site for the structurally related aminosteroid-based myorelaxants pancuronium and rapacuronium. Membrane cholesterol competes with neurosteroids/neuroactive steroids binding to both high- and low-affinity binding site, indicating that both sites are oriented towards the cell membrane..

• MeSH
• alosterická regulace účinky léků   fyziologie   MeSH
• androstany metabolismus   farmakologie   MeSH
• androsteny metabolismus   farmakologie   MeSH
• benzimidazoly metabolismus   farmakologie   MeSH
• CHO buňky MeSH
• cholesterol metabolismus   MeSH
• Cricetulus MeSH
• křečci praví MeSH
• lidé MeSH
• nedepolarizující myorelaxancia metabolismus   farmakologie   MeSH
• neurosteroidy metabolismus   MeSH
• receptory muskarinové metabolismus   MeSH
• triethojodid gallaminia metabolismus   farmakologie   MeSH
• vazebná místa účinky léků   fyziologie   MeSH
• vekuronium analogy a deriváty   metabolismus   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

1. Giant liver fluke Fascioloides magna is a dangerous parasite, which infects herbivores. It was imported to Europe from North America and started to spread. Benzimidazoles like albendazole, mebendazole, triclabendazole and salicylanilides closantel and rafoxanide are the most used anthelmintics to control fascioloidosis. However their effect might be altered via drug-metabolizing enzymes of this parasite. 2. The aim of our study was to determine the activities of drug-metabolizing enzymes in F. magna and the metabolism of above mentioned anthelmintics. 3. Activities of several oxidative, reductive and conjugative enzymes towards various model xenobiotic substrates were found in F. magna subcellular fractions. 4. Subcellular fractions from F. magna oxidized albendazole to its sulphoxide metabolite and reduced mebendazole to hydroxyl-mebendazole. Under ex vivo conditions, only very-low concentrations of these compounds were detected using high-performance liquid chromatography/mass spectrometry. 5. The results indicate that the giant liver fluke possesses the active xenobiotic-metabolizing system. The overexpression of this system may play an important role in parasite resistance against these anthelmintics.

• MeSH
• albendazol metabolismus   MeSH
• anthelmintika metabolismus   MeSH
• benzimidazoly metabolismus   MeSH
• Fasciola hepatica účinky léků   enzymologie   MeSH
• mebendazol metabolismus   MeSH
• rafoxanid metabolismus   MeSH
• salicylanilidy metabolismus   MeSH
• sulfoxidy metabolismus   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• xenobiotika metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Benzimidazoles anthelmintics, which enter into environment primarily through excretion in the feces or urine of treated animals, can affect various organisms and disrupt ecosystem balance. The present study was designed to test the phytotoxicity and biotransformation of the three benzimidazole anthelmintics albendazole (ABZ), fenbendazole (FBZ) and flubendazole (FLU) in the harebell (Campanula rotundifolia). This meadow plant commonly grows in pastures and comes into contact with anthelmintics through the excrements of treated animals. Suspensions of harebell cells in culture medium were used as an in vitro model system. ABZ, FLU and FBZ were not found to be toxic for harebell cells, which were able to metabolize ABZ, FLU and FBZ via the formation of a wide scale of metabolites. Ultrahigh-performance liquid chromatography coupled with high mass accuracy tandem mass spectrometry (UHPLC-MS/MS) led to the identification of 24, 18 and 29 metabolites of ABZ, FLU and FBZ, respectively. Several novel metabolites were identified for the first time. Based on the obtained results, the schemes of the metabolic pathways of these anthelmintics were proposed. Most of these metabolites can be considered deactivation products, but a substantial portion of them may readily be decomposed to biologically active substances which could negatively affect ecosystems.

• MeSH
• albendazol metabolismus   MeSH
• anthelmintika chemie   metabolismus   MeSH
• benzimidazoly chemie   metabolismus   MeSH
• biotransformace MeSH
• Campanulaceae cytologie   metabolismus   MeSH
• ekosystém MeSH
• feces chemie   MeSH
• fenbendazol metabolismus   MeSH
• kultivované buňky MeSH
• mebendazol analogy a deriváty   metabolismus   MeSH
• metabolické sítě a dráhy * MeSH
• tandemová hmotnostní spektrometrie metody   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Benzimidazole anthelmintics, the drugs against parasitic worms, are widely used in human as well as veterinary medicine. Following excretion, these substances may persist in the environment and impact non-target organisms. In order to test phytoremediation as a possible tool for detoxification of anthelmintics in environment, the biotransformation pathways of albendazole (ABZ) and flubendazole (FLU) were studied in reed (Phragmites australis) in vitro. Reed cells were able to uptake and biotransform both anthelmintics. Ten ABZ metabolites and five FLU metabolites were found. Some atypical biotransformation reactions (formation of glucosylglucosides, acetylglucosides and xylosylglucosides), which have not been described previously, were identified. Based on the obtained results, the schemes of metabolic pathways of ABZ and FLU in reed were proposed. Most of ABZ and FLU metabolites can be considered as anthelmintically less active; therefore uptake and biotransformation of these anthelmintics by reed could be useful for decrease of their toxicity in environment.

• MeSH
• albendazol chemie   metabolismus   MeSH
• anthelmintika chemie   metabolismus   MeSH
• benzimidazoly chemie   metabolismus   MeSH
• biodegradace MeSH
• biotransformace MeSH
• lidé MeSH
• lipnicovité cytologie   metabolismus   MeSH
• mebendazol analogy a deriváty   chemie   metabolismus   MeSH
• metabolická inaktivace * MeSH
• metabolické sítě a dráhy MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Inhibition of cyclin-dependent kinases by specific small molecules, purine cyclin-dependent kinase inhibitors (CDKi), has become a promising strategy for cancer treatment. Although pharmacodynamic properties of these compounds have been studied extensively, their pharmacokinetic behavior has not been addressed in detail. In this study, we investigated possible inhibitory effect of five purine CDKi on breast cancer resistance protein (ABCG2) transport activity employing in vitro transport and accumulation methods in MCDKII cells transduced with human ABCG2. Hoechst 33342 and glyburide were used as model ABCG2 substrates for these experiments. In addition, in situ method of dually perfused rat term placenta was utilized to confirm our in vitro results at the organ level. Fumitremorgin C was used as a model inhibitor of ABCG2 for comparison purposes. We demonstrate significant inhibition of ABCG2 by four of the five CDKi tested. Regarding their ABCG2-inhibitory potencies, the investigated compounds can be ranked as follows: purvalanol A>olomoucine II≈fumitremorgin C>roscovitine≈bohemine, with slight differences among substrates, concentrations and methods used. Based on our findings, it is reasonable to expect a substantial impact of the studied CDKi on the pharmacokinetic and pharmacodynamic behavior of concomitantly administered ABCG2 substrates. Moreover, using combination index method of Chou-Talalay, we confirmed that the strongest inhibitors, purvalanol A and olomoucine II, can synergistically potentiate cytostatic effect of mitoxantrone, an ABCG2 substrate, in ABCG2 expressing cell lines.

• MeSH
• ABC transportéry antagonisté a inhibitory   metabolismus   MeSH
• benzimidazoly metabolismus   MeSH
• buněčné linie MeSH
• chemorezistence účinky léků   MeSH
• cyklin-dependentní kinasy antagonisté a inhibitory   MeSH
• cytostatické látky farmakologie   MeSH
• glibenklamid metabolismus   MeSH
• lidé MeSH
• mitoxantron farmakologie   MeSH
• nádorové proteiny antagonisté a inhibitory   metabolismus   MeSH
• nádory prsu farmakoterapie   MeSH
• protinádorové látky farmakologie   MeSH
• puriny farmakologie   MeSH
• synergismus léků MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Od roku 2008 jsou dosud v platnosti světově uznávaná doporučení týkající se prevence a léčby tromboembolické nemoci (TEN). Od těchto 8. ACCP (American College of Chest Physicians) guidelines se pak odvíjejí národní doporučení, zabývající se mnoha aspekty tromboembolické nemoci. Zejména však v prevenci TEN byly od posledního vydání registrovány nové léky, které mění dosavadní léčebné praktiky. Vývoj nových účinných antikoagulancií se zaměřil na přímé inhibitory trombinu a přímé inhibitory faktoru Xa. Z prvé skupiny je již pro klinické užití, tj. prevenci tromboembolických příhod v ortopedii, schválen dabigatran (Pradaxa), rivaroxaban (Xarelto) a před registrací v ČR je apixaban (Eliquis). Ostatní molekuly jsou zatím ve stadiu klinického hodnocení (např. betrixaban, edoxaban, otomixaban). Výsledky dosavadních studií jsou velmi slibné, například při srovnání s nízkomolekulárními hepariny byl v profylaxi tromboembolických příhod u operací velkých kloubů rivaroxaban dvakrát účinnější proti enoxaparinu, v prevenci mozkových příhod u nemocných s fibrilací síní byly dabigatran i rivaroxaban, při srovnání s warfarinem, účinnější. Důležité je, že jde o perorální přípravky působící cíleně, a sice blokádou jednotlivých faktorů koagulační kaskády – faktoru Xa (xabany) a faktoru II (gatrany). V léčbě tromboembolické nemoci jsou stále základem nízkomolekulární hepariny, přičemž přínosem je možnost jejich léčebné aplikace v režimu jedenkrát denně, v ambulantní i nemocniční péči (Clexane Forte, Fraxiparin Forte, Zibor inj.).

Since 2008, internationally recognized guidelines have been in effect regarding the prevention and treatment of thromboembolic disease (TED). The national guidelines dealing with numerous aspects of thromboembolic disease are then based on these 8th ACCP Guidelines. However, new drugs, particularly in the prevention of TED, have been registered since the latest issue that alter the previous therapeutic practices. The development of new effective anticoagulant drugs has focused on direct thrombin inhibitors and direct factor Xa inhibitors. From the former group, dabigatran has been approved for clinical use, i.e. for the prevention of thromboembolic events in orthopaedics; from the latter group, rivaroxaban has been approved and apixaban is about to be registered in the Czech Republic. The other molecules have so far been in the phase of clinical testing (e. g. betrixaban, edoxaban, otamixaban). The results of studies conducted so far are very promising; for instance, when compared to low-molecular-weight heparins, rivaroxaban was twice as effective as enoxaparin in the prophylaxis of thromboembolic events in major joint surgery; both dabigatran and rivaroxaban were more effective in preventing stroke in patients with atrial fibrillation when compared to warfarin. Importantly, these are oral agents with targeted action, blocking the individual factors of the coagulation cascade, i. e. factor Xa (xabans) and factor II (gatrans). Low-molecular-weight heparins remain the mainstay of treatment of thromboembolic disease, with the benefit of having the possibility to be administered as a once-daily regimen, in both outpatient and inpatient care (Clexane Forte, Fraxiparine Forte, Zibor injections).

• Klíčová slova
• nízkomolekulární hepariny, dabigatran etexilát, apixaban, idraparinux,
• MeSH
• antikoagulancia farmakologie   terapeutické užití   MeSH
• aplikace orální MeSH
• benzimidazoly aplikace a dávkování   metabolismus   terapeutické užití   MeSH
• faktor Xa terapeutické užití   MeSH
• heparin nízkomolekulární aplikace a dávkování   farmakologie   terapeutické užití   MeSH
• hodnocení rizik MeSH
• hospitalizovaní pacienti MeSH
• inhibitory faktoru Xa MeSH
• lidé MeSH
• morfoliny aplikace a dávkování   farmakokinetika   terapeutické užití   MeSH
• oligosacharidy terapeutické užití   MeSH
• premedikace metody   MeSH
• pyrazoly aplikace a dávkování   farmakokinetika   terapeutické užití   MeSH
• pyridiny aplikace a dávkování   metabolismus   terapeutické užití   MeSH
• pyridony aplikace a dávkování   farmakokinetika   terapeutické užití   MeSH
• rivaroxaban MeSH
• rizikové faktory MeSH
• thiofeny aplikace a dávkování   farmakokinetika   terapeutické užití   MeSH
• tromboembolie farmakoterapie   prevence a kontrola   MeSH
• věkové faktory MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• přehledy MeSH

Benzetheno adducts derived from p-benzoquinone (p-BQ), a reactive metabolite of benzene, were reported to be formed by the reaction of p-BQ with DNA in vitro but have never been detected either in vivo or in experiments with living cells. Two of them, 3-hydroxy-3,N(4)-benzetheno-2'-deoxycytidine (DCBQ) and 7-hydroxy-1,N(2)-benzetheno-2'-deoxyguanosine (DGBQ), were administered to rats by single ip injections at the doses of 2 mg/kg each. The excretion of unchanged compounds DCBQ and DGBQ within 2 days amounted to 8.2 ± 1.9 and 4.5 ± 1.2% (mean ± SE) of the dose, respectively. Additionally, deribosylated metabolites of DCBQ and DGBQ, 3-hydroxy-3,N(4)-benzethenocytosine (CBQ) and 7-hydroxy-1,N(2)-benzethenoguanine (GBQ), were found amounting to 45.7 ± 10.2 and 2.9 ± 2.1% of the dose, respectively. An additional portion of CBQ and GBQ was liberated from their corresponding conjugates by acidic hydrolysis. Therefore, total recoveries of CBQ and GBQ in urine were 82.1 ± 13.5 and 11.6 ± 5.1% of the dose. To identify conjugated metabolites, DCBQ and DGBQ were administered intraperitoneally at the doses 10.5 and 11.0 mg/kg, respectively, to one animal each. Glucuronides of DCBQ, DGBQ, and GBQ as well as sulfates of DGBQ, CBQ, and GBQ were identified by ESI-LC-MS according to (M - H)(-) ions and their fragmentation. In addition, two oxygenated metabolites and their corresponding conjugates were detected for DGBQ and GBQ. One of these metabolites was identified as 2,7-dihydroxy-1,N(2)-benzethenoguanine OGBQ1. It coeluted with the product obtained by the reaction of HQ and p-BQ mixture with 8-hydroxy-2'-deoxyguanosine followed by acid hydrolysis. These findings suggest that both DCBQ and DGBQ undergo extensive biotransformation in vivo. CBQ appears to be the only p-BQ derived DNA adduct, which can be efficiently recovered from its conjugates and might be therefore useful in molecular dosimetry of benzene.

• MeSH
• adukty DNA chemie   metabolismus   MeSH
• benzen metabolismus   MeSH
• benzimidazoly chemie   metabolismus   moč   MeSH
• benzochinony chemie   MeSH
• časové faktory MeSH
• deoxycytidin analogy a deriváty   chemie   metabolismus   moč   MeSH
• deoxyguanosin analogy a deriváty   chemie   metabolismus   moč   MeSH
• DNA chemie   metabolismus   MeSH
• hmotnostní spektrometrie MeSH
• injekce intraperitoneální MeSH
• krysa rodu rattus MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• benzimidazoly agonisté   metabolismus   MeSH
• bifenylové sloučeniny metabolismus   terapeutické užití   MeSH
• blokátory receptorů AT1 pro angiotensin II farmakologie   MeSH
• diabetes mellitus 2. typu metabolismus   MeSH
• finanční podpora výzkumu jako téma MeSH
• hypertenze metabolismus   terapie   MeSH
• inzulinová rezistence MeSH
• lidé MeSH
• losartan analogy a deriváty   metabolismus   terapeutické užití   MeSH
• metabolický syndrom metabolismus   terapie   MeSH
• tetrazoly metabolismus   terapeutické užití   MeSH
• Check Tag
• lidé MeSH