Among numerous adducts formed by reaction of DNA with p-benzoquinone (p-BQ), an electrophilic metabolite of benzene, only N2-(4-hydroxyphenyl)guanine (N2HPG) has been confirmed in vivo. If excreted in urine N2HPG would be a candidate non-invasive biomarker of the DNA damage caused by benzene. To test this hypothesis, biotransformation of N2HPG was studied in rats. Unchanged N2HPG in urine amounted to 8.0 ± 2.2% and 9.1 ± 1.7% (mean ± SE) at the dose of 2 mg/kg excreted within 1 and 2 days after ip dosage, respectively. After acidic hydrolysis of the urine a slight but consistent increase in urinary N2HPG to 9.5 ± 3.2% and 11 ± 2.6% of dose was found within 1 and 2 days, respectively, indicating formation of hydrolysable conjugates. An oxidised metabolite was detected by LC-ESI-MS and identified by comparison with authentic standard as N2-(4-hydroxyphenyl)-8-oxoguanine (N2HPOG). Its excretion amounted to 2.7 ± 0.2% of dose and increased to 12.0 ± 2.7% of dose when N2HPOG was released from its conjugates by acidic hydrolysis. Glucuronides and sulphates of both N2HPG and N2HPOG were confirmed in urine by LC-ESI-MS and by enzymatic treatment with glucuronidase/sulphatase. These results indicate an extensive metabolism of N2HPG in vivo, which must be taken into account when considering N2HPG as a possible biomarker of exposure to benzene.

• MeSH
• adukty DNA chemie   metabolismus   farmakokinetika   moč   MeSH
• benzochinony metabolismus   MeSH
• biologické markery chemie   metabolismus   moč   MeSH
• biotransformace MeSH
• glukuronidasa metabolismus   MeSH
• glukuronidy chemie   metabolismus   moč   MeSH
• guanin analogy a deriváty   chemie   metabolismus   farmakokinetika   moč   MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
• hydrolýza MeSH
• karcinogeny metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• krysa rodu rattus MeSH
• oxidace-redukce MeSH
• potkani Wistar MeSH
• sírany chemie   metabolismus   moč   MeSH
• sulfatasy metabolismus   MeSH
• tandemová hmotnostní spektrometrie MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Putative endophytes of Miscanthus × giganteus were isolated, and screened in the laboratory, greenhouse and field for their plant growth promoting properties in this host. Pantoea ananatis and Pseudomonas savastanoi were the predominant bacteria in leaves whereas other pseudomonads prevailed in roots. Almost all fungal endophytes belonged to the Pezizomycotina and most were isolated from roots; Fusarium oxysporum was most abundant, followed by the genera Periconia, Exophiala, Microdochium and Leptodontidium. All endophytic groups produced phytohormones and some bacteria also produced siderophores, solubilised P and exhibited ACC-deaminase activity in vitro. In subsequent pot experiments with pre-selected endophytes, several isolates including pseudomonads, Variovorax paradoxus, Verticillium leptobactrum, Halenospora sp. and Exophiala sp. enhanced Miscanthus growth in gamma-sterilised soil. These promising Miscanthus-derived isolates were tested either as single or mixed inocula along with a mixed bacterial inoculum originating from poplar. No significant effects of inocula were detected in a pot experiment in non-sterilised soil. On two marginal field sites the mixture of bacterial endophytes from poplar had a consistently negative effect on survival and growth of Miscanthus. Contrarily, mixtures consisting of bacteria or fungi originating from Miscanthus promoted growth of their host, especially on the heavy metals-polluted site. The combination of bacteria and fungi was inferior to the mixtures consisting of bacteria or fungi alone. Our observations indicate extensive potential of mixed bacterial and fungal endophytic inocula to promote establishment and yield of Miscanthus grown on marginal and polluted land and emphasise the necessity to test particular microbial-plant host combinations. Morphotypes of fungi isolates from Miscanthus × giganteus.

• MeSH
• Ascomycota MeSH
• Bacteria klasifikace   genetika   izolace a purifikace   metabolismus   MeSH
• DNA bakterií genetika   MeSH
• DNA fungální genetika   MeSH
• endofyty klasifikace   genetika   izolace a purifikace   fyziologie   MeSH
• houby klasifikace   genetika   izolace a purifikace   fyziologie   MeSH
• kořeny rostlin mikrobiologie   MeSH
• látky znečišťující půdu * MeSH
• lipnicovité mikrobiologie   MeSH
• listy rostlin mikrobiologie   MeSH
• Populus mikrobiologie   MeSH
• půda chemie   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• siderofory metabolismus   MeSH
• těžké kovy MeSH
• vývoj rostlin * MeSH
• znečištění životního prostředí MeSH
• Publikační typ
• časopisecké články MeSH

Metabolism of benzene, an important environmental and industrial carcinogen, produces three electrophilic intermediates, namely, benzene oxide and 1,2- and 1,4-benzoquinone, capable of reacting with the DNA. Numerous DNA adducts formed by these metabolites in vitro have been reported in the literature, but only one of them was hitherto identified in vivo. In a search for urinary DNA adducts, specific LC-ESI-MS methods have been developed for the determination in urine of six nucleobase adducts, namely, 7-phenylguanine, 3-phenyladenine, 3-hydroxy-3,N(4) -benzethenocytosine, N(2) -(4-hydroxyphenyl)guanine, 7-(3,4-dihydroxyphenyl)guanine and 3-(3,4-dihydroxyphenyl)-adenine (DHPA), with detection limits of 200, 10, 260, 50, 400 and 200 pg ml(-1) , respectively. Mice were exposed to benzene vapors at concentrations of 900 and 1800 mg m(-3) , 6 h per day for 15 consecutive days. The only adduct detected in their urine was DHPA. It was found in eight out of 30 urine samples from the high-exposure group at concentrations of 352 ± 146 pg ml(-1) (mean ± SD; n = 8), whereas urines from the low-exposure group were negative. Assuming the DHPA concentration in the negative samples to be half of the detection limit, conversion of benzene to DHPA was estimated to 2.2 × 10(-6) % of the absorbed dose. Thus, despite the known high mutagenic and carcinogenic potential of benzene, only traces of a single DNA adduct in urine were detected. In conclusion, DHPA is an easily depurinating adduct, thus allowing indication of only high recent exposure to benzene, but not long-term damage to DNA in tissues.

• MeSH
• adenin analogy a deriváty   moč   MeSH
• adukty DNA moč   MeSH
• aplikace inhalační MeSH
• benzen toxicita   MeSH
• biologické markery MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
• hmotnostní spektrometrie MeSH
• karcinogeny toxicita   MeSH
• myši MeSH
• referenční standardy MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• chirurgie MeSH

• Konspekt
• Ortopedie. Chirurgie. Oftalmologie
• NLK Obory
• chirurgie

Příručka je určena vychovatelkám v družinách mládeže, které z ní mohou čerpat pestrý výběr her pohybových, tělocvičných, didaktických, pro cvičení postřehu, paměti, zručnosti, důvtipu. Soustředuje i zábavy, hlavolamy a kvizy s nejrůznějšími náměty. Text je metodicky uspořádán a opatřen teoretickými vysvětlivkami.

• MeSH
• dětský domov MeSH
• hra a hračky MeSH
• volnočasové aktivity MeSH
• výchova a vzdělávání MeSH
• Publikační typ
• příručky MeSH

• Konspekt
• Sport. Hry. Tělesná cvičení
• NLK Obory
• pedagogika
• zájmy a záliby

Ucelené moderní informace pro lékaře všech specializací z oblasti prevence poruch a nemocí.

• MeSH
• geriatrie MeSH
• poruchy chování u dětí MeSH
• primární prevence MeSH
• rizikové faktory MeSH
• týmová péče o pacienty MeSH
• vývoj dítěte MeSH
• vzdělávání pacientů jako téma MeSH

• Konspekt
• Veřejné zdraví a hygiena
• NLK Obory
• veřejné zdravotnictví
• sociální lékařství
• všeobecné lékařství