Mathematical analytical model of the processes running in individual radical clusters during the chemical phase (under the presence of radiomodifiers) proposed by us earlier has been further developed and improved. It has been applied to the data presented by Blok and Loman characterizing the oxygen effect in SSB and DSB formation (in water solution and at low-LET radiation) also in the region of very small oxygen concentrations, which cannot be studied with the help of experiments done with living cells. In this new analysis the values of all reaction rates and diffusion parameters known from literature have been made use of. The great increase of SSB and DSB at zero oxygen concentration may follow from the fact that at small oxygen concentrations the oxygen absorbs other radicals while at higher concentrations the formation of oxygen radicals prevails. It explains the double oxygen effect found already earlier by Ewing. The model may be easily extended to include also the effects of other radiomodifiers present in medium during irradiation.
- MeSH
- bakteriofág phi X 174 genetika účinky záření MeSH
- biologické modely * MeSH
- chromozomy účinky léků účinky záření MeSH
- difuze účinky léků účinky záření MeSH
- dvouřetězcové zlomy DNA účinky léků účinky záření MeSH
- ionizující záření * MeSH
- kyslík farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kyslík MeSH
The research of microorganisms includes the development of methods for the inactivation of viruses and other microbes. It also means to efficiently eliminate the infectivity of microorganisms without damage of their integrity and structure. According to the results of the last 5 years the capillary electromigration techniques appear to be very perspective for the comparison of the methods applicable for inactivation in the diagnostics and study of the pathogens. In this paper we suggest the capillary isoelectric focusing of the model microorganisms, Escherichia coli, Staphylococcus epidermidis, Candida albicans and bacteriophage PhiX 174, native or inactivated by different procedures. UV detection and fluorometric detection for the dynamically modified microbes by pyrenebutanoate on the basis of the non-ionogenic tenside were used here. Isoelectric points of native and/or dynamically modified microorganisms and other properties were compared with those obtained after microorganisms inactivation. The segmental injection of the sample pulse enabled the reproducible and efficient capillary isoelectric focusing in different pH gradients. The low-molecular-weight pI markers were used for tracing of the pH gradient.
- MeSH
- Bacteria účinky léků MeSH
- bakteriofág phi X 174 účinky léků MeSH
- Candida albicans účinky léků MeSH
- elektroforéza kapilární metody MeSH
- Escherichia coli účinky léků MeSH
- isoelektrická fokusace metody MeSH
- izoelektrický bod MeSH
- mikrobiální viabilita MeSH
- pilotní projekty MeSH
- povrchově aktivní látky farmakologie MeSH
- Staphylococcus epidermidis účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- povrchově aktivní látky MeSH
Ultraviolet light is known to generate crosslinks between the complementary strands of DNA and between DNA and proteins. Here we demonstrate that the UV light also crosslinks DNA duplexes to other DNA duplexes. However, the duplex-to-duplex crosslinks only appear in the presence of about 75% (vol/vol) ethanol plus a millimolar or submillimolar concentration of monovalent or divalent cations, e.g. 2 mM Na+. Methanol or formamide are ineffective. The present observations provide a direct means to detect physical contacts of DNA molecules or their parts, e.g. during recombination. It is remarkable that the solution conditions leading to the duplex-to-duplex UV light-induced crosslink formation are the same as those inducing the B-to-A conformational transition of DNA.
- MeSH
- bakteriofág phi X 174 MeSH
- DNA virů chemie účinky léků účinky záření MeSH
- ethanol farmakologie MeSH
- formamidy farmakologie MeSH
- kationty dvojmocné farmakologie MeSH
- kationty jednomocné farmakologie MeSH
- methanol farmakologie MeSH
- plazmidy chemie účinky léků účinky záření MeSH
- reagencia zkříženě vázaná MeSH
- restrikční mapování MeSH
- roztoky MeSH
- sekvence nukleotidů MeSH
- ultrafialové záření * MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- DNA virů MeSH
- ethanol MeSH
- formamide MeSH Prohlížeč
- formamidy MeSH
- kationty dvojmocné MeSH
- kationty jednomocné MeSH
- methanol MeSH
- reagencia zkříženě vázaná MeSH
- roztoky MeSH
- voda MeSH
The relative amounts of DNA fragments in a mixture injected into the capillary by electromigration or hydrodynamically by pressure were compared. Even if the electrophoretic mobilities of DNA fragments with different sizes are the same in a free solution in the sample vial, the size bias is brought about by the different mobilities in a sieving medium and by the electroosmosis. The experiments were performed in capillaries filled with a solution of liquified agarose, a replaceable sieving medium. The experimental results were compared with a theoretical model.
- MeSH
- bakteriofág phi X 174 chemie MeSH
- DNA virů chemie MeSH
- DNA chemie MeSH
- elektrochemie MeSH
- elektroforéza v agarovém gelu MeSH
- teoretické modely MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- DNA virů MeSH
- DNA MeSH
The paper documents the high resistance of E. coli phage phi X 174, one of the small non-enveloped viruses of icosahedral symmetry, vis-a-vis certain physico-chemical factors. It is this property that makes the phage a suitable model for evaluating in practical terms the efficiency of antisepsis, disinfection and chemical sterilization. The phage is detected in smears, prints and on carriers using the plaque method. The system E. coli--phage phi X 174 may serve as a bioindicator of the viricidal efficiency of chemical sterilization eventually of the measure of absorbance of sterilizing agents on the treated material.
- MeSH
- antiinfekční látky lokální farmakologie MeSH
- bakteriofág phi X 174 účinky léků MeSH
- dezinfekce rukou metody MeSH
- dezinficiencia farmakologie MeSH
- hodnotící studie jako téma MeSH
- lidé MeSH
- sterilizace metody MeSH
- viry účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antiinfekční látky lokální MeSH
- dezinficiencia MeSH
Specific interactions of DNA with proteins are required for both the replication of deoxyribonucleic acid proper and its regulation. Genetic elements of bacteria, their extrachromosomal elements in particular, represent a suitable model system for studies of these processes at the molecular level. In addition to replication enzymes (DNA polymerases), a series of other protein factors (e.g. topoisomerases, DNA unwinding enzymes, and DNA binding proteins) are involved in the replication of the chromosomal, phage and plasmid DNA. Specific interactions of proteins with DNA are particularly important in the regulation of initiation of DNA synthesis. Association of DNAs with the cell membrane also plays an important role in their replication in bacteria.
- MeSH
- bakteriální chromozomy fyziologie MeSH
- bakteriální geny MeSH
- bakteriální proteiny genetika MeSH
- bakteriální RNA genetika MeSH
- bakteriofág phi X 174 genetika MeSH
- DNA bakterií genetika MeSH
- DNA řízené RNA-polymerasy metabolismus MeSH
- DNA-dependentní DNA-polymerasy metabolismus MeSH
- DNA biosyntéza MeSH
- Escherichia coli genetika metabolismus MeSH
- plazmidy MeSH
- replikace DNA * MeSH
- T-fágy genetika MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- bakteriální proteiny MeSH
- bakteriální RNA MeSH
- DNA bakterií MeSH
- DNA řízené RNA-polymerasy MeSH
- DNA-dependentní DNA-polymerasy MeSH
- DNA MeSH
- Okazaki fragments MeSH Prohlížeč
A method was developed for evaluating the viricidal effectiveness of chemical disinfectants. The method uses the DNA bacteriophage phi X 174 (ATCC 13706-B1), whose host is Escherichia coli C (ATCC 13706-1), as the model virus. The bacteriophage has particles of icosahedral symmetry, 26 nm in diameter, and resembles animal entero- and parvoviruses by its resistance to physicochemical factors. Disinfection effectiveness was evaluated in suspension medium and on carriers of different materials that are disinfected in practice. The Horvath-Alföldi method on plexiglass panels containing 21 dishes of 40-mm diameter and 2-mm depth was used. A volume of 0.2 ml of phage suspension or one flat carrier 25 mm X 25 mm was put per panel dish and overlaid with 3 ml of dissolved soft agar medium containing at 37 degrees C, quantitatively as VE = log (No/Nd) in suspension tests and semiquantitatively on a 0-5 scale in tests on carrier materials. The viricidal effect of disinfectant-containing washing agents was tested on textile carriers during washing in an experimental washing machine. The method can be adjusted to evaluate the viricidal effectiveness of disinfection under different environmental conditions, e.g. in sanitary, agricultural, veterinary or food-industry facilities.
- MeSH
- bakteriofág phi X 174 účinky léků MeSH
- biologické modely * MeSH
- dezinfekce metody MeSH
- dezinficiencia farmakologie MeSH
- sterilizace metody MeSH
- textilie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- dezinficiencia MeSH
Performic acid HCOOH (PFA) is a wide-spectrum disinfectant. It inactivates viruses, bacteria and bacterial spores, mycobacteria as well as microscopic fungi. Its main drawback is its instability, which makes it a logical necessity that it is to be prepared prior to use from its components HCOOH and H2O2. The mixing of 8 ml HCOOH of the concentration 850 ml/l and 17 ml H2O2 of the concentration 300 ml/l in a 100 ml-volume reagent bottle with a ground-in glass stopper gives, after an 1-hour rest at room temperature and after another 1 hour in a refrigerator, a stock solution that contains about 50 ml/l of PFA the actual concentration of which is determined iodometrically. Bacteriophage phi X 174 (host E. coli C) is characterized by cubic ikosahedral-type symmetry of particles free of envelope, has 27 mm in diameter and contains single-strand cyclic DNA; formerly was classed among Parvoviridae. The possibility of plaque assay-based quantitative determination of the number of infectious particles makes if it a feasible model for assessing disinfectant action on small hydrophilic viruses under conditions close to those of practical disinfection procedures. PFA stock solution diluted to 1 X 10(-3) (0.05 ml/l of effective component) inactivates the model virus of a concentration 10(8) pfu/ml aqueous suspension within 5 min so that no virus is detectable; the drop in the number of pfu amounts to 7 log orders of magnitude. In the presence of 400 ml/l of serum, the identical effect is achieved within 5 min by PFA stock solution diluted to 5 X 10(-3). The lowest PFA concentration that reliably inactivates bacteriophage phi X 174 in aqueous suspension is identical with the lowest concentration inactivating Coxsackie B 1 virus in tissue cultures. On textile, glass, plastic, rubber and metal carriers contaminated by swabbing or by a dried drop of bacteriophage suspension containing about 1 X 10(9) pfu/ml, the lowest reliably effective concentrations of PFA range within 0.25-0.025 ml/l, i.e. PFA stock solutions diluted to 5 X 10(-3)-5 X 10(-4), depending on the type of carrier and the type of contamination.
- MeSH
- bakteriofág phi X 174 účinky léků MeSH
- dezinfekce metody MeSH
- dezinficiencia farmakologie MeSH
- formiáty farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- dezinficiencia MeSH
- formiáty MeSH
- peroxyformic acid MeSH Prohlížeč
