Search results for "Autor"
showing 10 items of 820 documents
The autoradiographic test for unscheduled DNA synthesis: a sensitive assay for the detection of DNA repair in the HepG2 cell line
2004
International audience; We assessed the DNA-repair capacity of HepG2 cells, which were derived from a human hepatoma, by the unscheduled DNA synthesis assay, using the autoradiography protocol (UDS-AR). We evaluated DNA repair following exposure to direct mutagens (4-nitroquinoline-N-oxide (4-NQO), methyl methanesulfonate (MMS)), to mutagens requiring metabolic activation (benzo[a]pyrene (B[a]P), 2-acetylaminofluorene (2-AAF), N-dimethylnitrosoamine (NDMA)) or to structurally related non-mutagens such as pyrene and 4-acetylaminofluorene (4-AAF). All positive compounds tested induced UDS in HepG2 cells. With 4-NQO and MMS, a concentration-dependent increase in net nuclear grains per cell was…
Measurement of Lymphocyte Proliferation: Critical Analysis of Radioactive and Photometric Methods
1992
Different methods of lymphocyte proliferation are compared to identify a non-radioactive alternative to 3H-thymidine-test. The enzymatic assays evaluating the turnover of mitochondrial dehydrogenases (MTT-test) and lysosomal hexosaminidase (NAG-test) proved not sensitive enough to substitute for 3H-thymidine incorporation. The incorporation of the nucleotide analog 5-bromodeoxyuridine (BrdU) can be exploited using an ELISA-system (enzyme linked immunosorbent assay) employing a monoclonal anti-BrdU antibody to measure cell proliferation. An optimized test protocol of the BrdU-ELISA which fulfills the requirements for a sensitive and practicable non-radioactive alternative to 3H-thymidine-tes…
Survival in extreme dryness and DNA-single-strand breaks.
1992
A wide variety of organisms (the so-called "anhydrobiotes') is able to survive long periods of time in a state of utmost dehydration and can thus survive in extremely dry environments including artificially imposed or space vacuum. Known strategies of survival include the accumulation of certain polyols, especially disaccharides, which help prevent damage to membranes and proteins. Here we report that DNA in vacuum-dried spores is damaged to a very substantial degree by processes leading to DNA strand breaks. Most of these lesions are obviously repaired during germination, but extensive damage to DNA and enzymes after long exposure times (months to years) finally diminish the chances of sur…
Role of two operators in regulating the plasmid-borne raf operon of Escherichia coli
1994
The plasmid-borne raf operon encodes functions required for the inducible uptake and utilization of raffinose in Escherichia coli K12. The expression of three structural genes for alpha-galactosidase (rafA), Raf permease (rafB) and sucrose hydrolase (rafD) is negatively controlled by the binding of RafR repressor (rafR) to two operator sites, O1 and O2, that flank the -35 sequence of the raf promoter, PA. In vitro, O1 and O2 are occupied on increasing the concentration of RafR, without detectable preference for one site or the other or any indication of cooperative binding. Nucleotide substitutions at positions 3, 4 or 5 in an operator half-site prevented repressor binding, supporting a mod…
Digital image processing for rapid analysis of differentially expressed transcripts on high-density cDNA arrays.
1999
Usage of filter arrays is becoming increasingly attractive for many research laboratories involved in determination of gene-expression profiles. However, analysis of numerous spots, representing genes or partial gene sequences (ESTs), is still tedious work involving the ordered analysis of vast amounts of numerical tabular data. We present a rapid and efficient method for the visual identification of differentially expressed targets on high-density cDNA filter arrays using standard laboratory equipment and standard software, which is available for free. The method we introduce provides an inexpensive alternative, and no changes in the experimental set up are required. Our results were veri…
'Dual' Gravity: Using Spatial Econometrics to Control for Multilateral Resistance
2010
We propose a quantity-based `dual' version of the gravity equation that yields an estimating equation with both cross-sectional interdependence and spatially lagged error terms. Such an equation can be concisely estimated using spatial econometric techniques. We illustrate this methodology by applying it to the Canada-U.S. data set used previously, among others, by Anderson and van Wincoop (2003) and Feenstra (2002, 2004). Our key result is to show that controlling directly for spatial interdependence across trade flows, as suggested by theory, significantly reduces border effects because it captures `multilateral resistance'. Using a spatial autoregressive moving average specification, we …
Mašīnkoda instrumentēšana bloku izpildes statistiskajai analīzei un paredzēšanai
2019
Maģistra darba pirmajā daļā tika aprakstīti mašīnkoda apgrieztas inženierijas pielietojumi (autortiesību un komercnoslēpuma aizsardzība, ievainojamību meklēšana). Kā arī apskatīti binārās analīzes rīki, process un soļi. Darba otrajā daļā tika salīdzināta dažādu binārās analīzes metožu efektivitāte, un identificētās situācijas, kad ar esošām metodēm var būt nepietiekami. Darba trešajā daļā tika piedāvātā oriģināla metode – “starp-bloku varbūtisko pāreju grafs”. Tā papildina eksistējošo trasēšanas metožu sniegto ar izpildes vēstures statistisko analīzi. Pielietojot to praktiski, tika secināts, ka tā atsevišķos gadījumos var sniegt priekšrocības. Starp-bloku varbūtisko pāreju grafu var izmanto…
Fakultātes publikāciju reģistrs
2016
“Fakultātes publikāciju reģistrs” ir sistēma, kuras izstrādes mērķi ir uzturēt datus par fakultātē uzrakstītām publikācijām un rakstiem un glabāt ar tiem saistīto informāciju par to autoriem, indeksiem un citiem publikāciju atribūtiem, ka arī veikt datu eksportu. Sistēma ir domāta izmantošanai fakultātē, kas nodrošina iespēju cilvēkiem (sistēmas ietvaros autoriem) reģistrēties un pievienot savu publikāciju ierakstus. Visiem pārējiem ir iespēja apskatīt šos datus. Savukārt administratoram ir pieeja rediģēt visu ievadīto informāciju. Galvenais mērķis, kāpēc šī sistēma ir nepieciešama ir veikt datu eksportu failā.