Checkpoint-mediated dependency of tumor cells can be deployed to selectively kill them without substantial toxicity to normal cells. Specifically, loss of CHK1, a serine threonine kinase involved in the surveillance of the G2-M checkpoint in the presence of replication stress inflicted by DNA-damaging drugs, has been reported to dramatically influence the viability of tumor cells. CHK1's pivotal role in maintaining genomic stability offers attractive opportunity for increasing the selectivity, effectivity, and reduced toxicity of chemotherapy. Some recently identified CHK1 inhibitors entered clinical trials in combination with DNA antimetabolites. Herein, we report synthesis and profiling of MU380, a nontrivial analogue of clinically profiled compound SCH900776 possessing the highly unusual N-trifluoromethylpyrazole motif, which was envisioned not to undergo metabolic oxidative dealkylation and thereby provide greater robustness to the compound. MU380 is a selective and potent inhibitor of CHK1 which sensitizes a variety of tumor cell lines to hydroxyurea or gemcitabine up to 10 times. MU380 shows extended inhibitory effects in cells, and unlike SCH900776, does not undergo in vivo N-dealkylation to the significantly less selective metabolite. Compared with SCH900776, MU380 in combination with GEM causes higher accumulation of DNA damage in tumor cells and subsequent enhanced cell death, and is more efficacious in the A2780 xenograft mouse model. Overall, MU380 represents a novel state-of-the-art CHK1 inhibitor with high potency, selectivity, and improved metabolic robustness to oxidative N-dealkylation. Mol Cancer Ther; 16(9); 1831-42. ©2017 AACR.

• MeSH
• antitumorózní látky chemická syntéza   farmakologie   MeSH
• apoptóza účinky léků   MeSH
• biologické markery MeSH
• buněčný cyklus účinky léků   MeSH
• checkpoint kinasa 1 antagonisté a inhibitory   MeSH
• chemorezistence účinky léků   MeSH
• dealkylace účinky léků   MeSH
• inhibitory proteinkinas chemická syntéza   farmakologie   MeSH
• kontrolní body buněčného cyklu účinky léků   MeSH
• lidé MeSH
• metylace MeSH
• modely nemocí na zvířatech MeSH
• molekulární struktura MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• pyrazoly farmakologie   MeSH
• pyrimidiny farmakologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• xenogenní modely - testy antitumorózní aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

We studied sequence-dependent retention properties of synthetic 5'-terminal phosphate absent trinucleotides containing adenine, guanine and thymine through reversed-phase liquid chromatography (RPLC) and QSRR modelling. We investigated the influence of separation conditions, namely mobile phase composition (ion interaction agent content, pH and organic constituent content), on sequence-dependent separation by means of ion-interaction RPLC (II-RPLC) using two types of models: experimental design-artificial neural networks (ED-ANN), and linear regression based on molecular dynamics data. The aim was to determine those properties of the above-mentioned analytes responsible for the retention dependence of the sequence. Our results show that there is a deterministic relation between sequence and II-RPLC retention properties of the studied trinucleotides. Further, we can conclude that the higher the content of ion-interaction agent in the mobile phase, the more prominent these properties are. We also show that if we approximate the polar component of solvation energy in QSRR by the electrostatic work in transferring molecules from vacuum to water, and the non-polar component by the solvent accessible surface area, these parameters best describe the retention properties of trinucleotides. There are some exceptions to this finding, namely sequences 5'-NAN-3', 5'-ANN-3', 5'-TGN-3', 5'-NTA-3'and 5'-NGA-3' (N stands for generic nucleotide). Their role is still unknown, but since linear regression including these specific constellations showed a higher observable variance coverage than the model with only the basic descriptors, we may assume that solvent-analyte interactions are responsible for the exceptional behaviour of 5'-NAN-3' & 5'-ANN-3' trinucleotides and some intramolecular interactions of neighbouring nucleobases for 5'-TGN-3', 5'-NTA-3'and 5'-NGA-3' trinucleotides.

• MeSH
• adenin analogy a deriváty   izolace a purifikace   MeSH
• chromatografie s reverzní fází MeSH
• guanin analogy a deriváty   izolace a purifikace   MeSH
• kvantitativní vztahy mezi strukturou a aktivitou MeSH
• neuronové sítě (počítačové) MeSH
• oligonukleotidy izolace a purifikace   MeSH
• rozpouštědla MeSH
• simulace molekulární dynamiky MeSH
• statická elektřina MeSH
• thymin analogy a deriváty   izolace a purifikace   MeSH
• voda MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH

In this work aqueous infusions from ten Mentha herbal samples (four different Mentha species and six hybrids of Mentha x piperita) and 20 different peppermint teas were screened by capillary electrophoresis with UV detection. The fingerprint separation was accomplished in a 25 mM borate background electrolyte with 10% methanol at pH 9.3. The total polyphenolic content in the extracts was determined spectrophotometrically at 765 nm by a Folin-Ciocalteu phenol assay. Total antioxidant activity was determined by scavenging of 2,2-diphenyl-1-picrylhydrazyl radical at 515 nm. The peak areas of 12 dominant peaks from CE analysis, present in all samples, and the value of total polyphenolic content and total antioxidant activity obtained by spectrophotometry was combined into a single data matrix and principal component analysis was applied. The obtained principal component analysis model resulted in distinct clusters of Mentha and peppermint tea samples distinguishing the samples according to their potential protective antioxidant effect. Principal component analysis, using a non-targeted approach with no need for compound identification, was found as a new promising tool for the screening of herbal tea products.

• MeSH
• antioxidancia analýza   MeSH
• elektroforéza kapilární MeSH
• léčivé rostliny MeSH
• máta chemie   MeSH
• spektrofotometrie MeSH
• Publikační typ
• časopisecké články MeSH

Chromý a kol. v r. 2009 zjistili, že stanovení celkové sérové bílkoviny biuretovým činidlem za použití albuminových kalibrátorů, vypracované v r. 1981 Doumasovou pracovní skupinou jako kandidáta na referenční metodu, poskytuje výsledky s neakceptovatelnou systematickou pozitivní chybou, způsobenou zejména endogenním sérovým bilirubinem a lipidy. Zjistili též, že k nápravě stačí užít bíkovinné standardy na bázi séra nebo plasmy, které jsou komutabilní se vzorky pacientů, a jsou certifikovány Kjeldahlovou metodou. V našich dvou předchozích publikacích, (Chromý a kol., 2015 a Vinklárková a kol., 2015), jsme ověřili Kjeldahlovy postupy užívané v laboratorní medicíně. Zvolili jsme přímou analýzu ze sraženiny bílkovin promyté kyselinou trichloroctovou a prověřili jsme její analytické provozní parametry. V této práci popisujeme zjednodušenou analýzu s modifikovanou Kjeldahlovou digesční baňkou, kterou lze přímo připojit k tomu přizpůsobené Parnes-Wagnerově destilační aparatuře a uvádíme její validační parametry. Zjednodušenou Kjeldahlovu metodu navrhujeme jako standardní operační postup pro stanovení celkové bílkoviny v referenčních materiálech užívaných v klinické chemii.

Chromý et al. found in 2009, that albumin-calibrated analysis of serum total protein with biuret reagent according to a candidate reference method developed by Doumas working group in 1981, provide results with unacceptable positive bias, caused namely by endogeneous serum bilirubin and lipids. They also found, that a simplest way to rectify this defect, is the use of serum and/or plasma-based protein standards, commutable with patients samples, which are certified by the Kjeldahl method. In our foregoing two articles, (Chromý et al., 2015, and Vinklárková et al., 2015), we reviewed Kjeldahl methods adopted by laboratory medicine, selected a direct analysis on washed protein precipitates with trichloroacetic acid and verified its preliminary analytical performance parameters. In this article, we describe a simplified Kjeldahl analysis with modified digestion flask, now directly connectable to accordingly adapted Parnas and Wagner distillation unit, and present its re-validation. Simplified Kjeldahl method is suggested as a standard operating procedure for total protein in reference materials used in clinical chemistry.

• MeSH
• biochemická analýza krve * metody   normy   MeSH
• proteiny * analýza   MeSH
• referenční standardy * MeSH
• reprodukovatelnost výsledků MeSH
• směrnice jako téma MeSH

To select a Kjeldahl procedure suitable for the determination of total protein in reference materials used in laboratory medicine, we reviewed in our previous article Kjeldahl methods adopted by clinical chemistry and found an indirect two-step analysis by total Kjeldahl nitrogen corrected for its nonprotein nitrogen and a direct analysis made on isolated protein precipitates. In this article, we compare both procedures on various reference materials. An indirect Kjeldahl method gave falsely lower results than a direct analysis. Preliminary performance parameters qualify the direct Kjeldahl analysis as a suitable primary reference procedure for the certification of total protein in reference laboratories.

• MeSH
• klinická chemie přístrojové vybavení   metody   MeSH
• lidé MeSH
• proteiny chemie   MeSH
• referenční hodnoty MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

We found previously that albumin-calibrated total protein in certified reference materials causes unacceptable positive bias in analysis of human sera. The simplest way to cure this defect is the use of human-based serum/plasma standards calibrated by the Kjeldahl method. Such standards, commutative with serum samples, will compensate for bias caused by lipids and bilirubin in most human sera. To find a suitable primary reference procedure for total protein in reference materials, we reviewed Kjeldahl methods adopted by laboratory medicine. We found two methods recommended for total protein in human samples: an indirect analysis based on total Kjeldahl nitrogen corrected for its nonprotein nitrogen and a direct analysis made on isolated protein precipitates. The methods found will be assessed in a subsequent article.

• MeSH
• kalibrace MeSH
• klinická chemie metody   MeSH
• laboratoře MeSH
• lékařství MeSH
• lidé MeSH
• proteiny chemie   MeSH
• referenční hodnoty MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

A new method for rapid determination of toxic metabolites after methanol and ethylene glycol intoxication - oxalate, formate and glycolate in various body fluid samples (blood serum, saliva, urine, exhaled breath condensate) by capillary electrophoresis with contactless conductometric detection was developed. A selective separation of the three target analytes from other constituents present in the analyzed biological matrices was achieved in less than 6min in a fused silica capillary of 25μm I.D. using an electrolyte comprising 50mM l-histidine and 50mM 2-(N-morpholino)ethanesulfonic acid at pH 6.1. The only sample preparation was dilution with deionized water. The limits of detection were 0.4, 0.6 and 1.3μM and limits of quantitation 1.3, 1.9 and 4.2μM for oxalate, formate and glycolate, respectively. The method provides a simple and rapid diagnostic test in suspected intoxication and is able to distinguish the ingested liquid, based on its metabolite trace. The method presents a fast screening tool that can be applicable in clinical practice.

• MeSH
• elektroforéza kapilární metody   MeSH
• elektrolyty MeSH
• formiáty izolace a purifikace   MeSH
• glykoláty izolace a purifikace   MeSH
• lidé MeSH
• tělesné tekutiny chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Retention characteristics of selected synthetic 5'-terminal phosphate absent penta-nucleotides containing adenine, guanine, and thymine were studied in relation to their sequence by hydrophilic interaction chromatography and ion-interaction reversed-phase liquid chromatography. The organic solvent content, pH, and buffer concentration in mobile phases were evaluated as influential separation conditions. Data demonstrate that both compared chromatographic modes can be used to separate synthetic penta-nucleotides according to their nucleotide composition. Moreover, reversed-phase liquid chromatography allows separation according to their sequence. We have found a simple linear additive model to describe the retention order in both separation modes in regard to their sequence. In hydrophilic interaction chromatography, the retention behavior is controlled primarily by the hydrophilicity of involved nucleotides and minimally by their sequence position. For reversed-phase liquid chromatography, the nucleotide hydrophobicity plays an important role in their retention properties and the influence of their location in sequence on the retention increases toward the center and decreases toward the termini. Our results show that the penta-nucleotide sequence, and thus its spatial arrangement induced by the surrounding environment, is highly related to the retention properties, so it may be hypothetically used to read the sequence from the retention properties acquired under particular separation conditions.

• MeSH
• chromatografie kapalinová metody   MeSH
• chromatografie s reverzní fází metody   MeSH
• hydrofobní a hydrofilní interakce MeSH
• kinetika MeSH
• koncentrace vodíkových iontů MeSH
• oligonukleotidy chemická syntéza   chemie   MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH

Telomere homeostasis is regulated at multiple levels, including the local chromatin structure of telomeres and subtelomeres. Recent reports demonstrated that a decrease in repressive chromatin marks, such as levels of cytosine methylation in subtelomeric regions, results in telomere elongation in mouse cells. Here we show that a considerable fraction of cytosines is methylated not only in subtelomeric, but also in telomeric DNA of tobacco BY-2 cells. Drug-induced hypomethylation (demonstrated at subtelomeric, telomeric, and global DNA levels) results in activation of telomerase. However, in contrast to mouse cells, the decrease in 5-methylcytosine levels and upregulation of telomerase do not result in any changes of telomere lengths. These results demonstrate the involvement of epigenetic mechanisms in the multilevel process of regulation of telomerase activity in plant cells and, at the same time, they indicate that changes in telomerase activity can be overridden by other factors governing telomere length stability.

• MeSH
• adenin analogy a deriváty   farmakologie   MeSH
• aktivace enzymů účinky léků   MeSH
• cytidin analogy a deriváty   farmakologie   MeSH
• DNA rostlinná chemie   účinky léků   MeSH
• epigeneze genetická MeSH
• genetická transkripce účinky léků   MeSH
• kultivované buňky MeSH
• metylace DNA účinky léků   MeSH
• nukleozomy účinky léků   fyziologie   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• tabák cytologie   účinky léků   genetika   metabolismus   MeSH
• telomerasa metabolismus   MeSH
• telomery chemie   účinky léků   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• chemie analytická MeSH
• klinická chemie MeSH

• Konspekt
• Analytická chemie
• Učební osnovy. Vyučovací předměty. Učebnice
• NLK Obory
• chemie, klinická chemie
• NLK Publikační typ
• učebnice vysokých škol