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71.
Dorota Szczepanik Paweł Mackiewicz Maria Kowalczuk Agnieszka Gierlik Aleksandra Nowicka Mirosław R. Dudek Stanisław Cebrat 《Journal of molecular evolution》2001,52(5):426-433
One of the main causes of bacterial chromosome asymmetry is replication-associated mutational pressure. Different rates of
nucleotide substitution accumulation on leading and lagging strands implicate qualitative and quantitative differences in
the accumulation of mutations in protein coding sequences lying on different DNA strands. We show that the divergence rate
of orthologs situated on leading strands is lower than the divergence rate of those situated on lagging strands. The ratio
of the mutation accumulation rate for sequences lying on lagging strands to that of sequences lying on leading strands is
rather stable and time-independent. The divergence rate of sequences which changed their positions, with respect to the direction
of replication fork movement, is not stable—sequences which have recently changed their positions are the most prone to mutation
accumulation. This effect may influence estimations of evolutionary distances between species and the topology of phylogenetic
trees.
Received: 24 July 2000 / Accepted: 16 January 2001 相似文献
72.
H B Feldman P A Szczepanik P Havre R J Corrall L C Yu H M Rodman B A Rosner P D Klein B R Landau 《Biochimica et biophysica acta》1977,480(1):14-20
Placental aldose reductase (EC 1.1.1.21) was incubated with glucose in the presence of [4A-2H] NADPH prepared in the oxidation of [2-2H] isocitrate by isocitrate dehydrogenase (EC 1.1.1.42) or [4B-2H] NADPH prepared in the oxidation of [1-2H] glucose-6-phosphate dehydrogenase (EC 1.1.1.49). The sorbitol formed from [4A-2H] NADPH contained deuterium and from [4B-2H] NADPH it did not. Therefore, aldose reductase in an A-type enzyme. 相似文献
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Maryla Krajewska Layton H. Smith Juan Rong Xianshu Huang Marc L. Hyer Nikolajs Zeps Barry Iacopetta Steven P. Linke Allen H. Olson John C. Reed Stan Krajewski 《The journal of histochemistry and cytochemistry》2009,57(7):649-663
Cell death is of broad physiological and pathological importance, making quantification of biochemical events associated with cell demise a high priority for experimental pathology. Fibrosis is a common consequence of tissue injury involving necrotic cell death. Using tissue specimens from experimental mouse models of traumatic brain injury, cardiac fibrosis, and cancer, as well as human tumor specimens assembled in tissue microarray (TMA) format, we undertook computer-assisted quantification of specific immunohistochemical and histological parameters that characterize processes associated with cell death. In this study, we demonstrated the utility of image analysis algorithms for color deconvolution, colocalization, and nuclear morphometry to characterize cell death events in tissue specimens: (a) subjected to immunostaining for detecting cleaved caspase-3, cleaved poly(ADP-ribose)-polymerase, cleaved lamin-A, phosphorylated histone H2AX, and Bcl-2; (b) analyzed by terminal deoxyribonucleotidyl transferase–mediated dUTP nick end labeling assay to detect DNA fragmentation; and (c) evaluated with Masson''s trichrome staining. We developed novel algorithm-based scoring methods and validated them using TMAs as a high-throughput format. The proposed computer-assisted scoring methods for digital images by brightfield microscopy permit linear quantification of immunohistochemical and histochemical stainings. Examples are provided of digital image analysis performed in automated or semiautomated fashion for successful quantification of molecular events associated with cell death in tissue sections. (J Histochem Cytochem 57:649–663, 2009) 相似文献
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A B Szczepanik W J Rudowski A Misiak 《Polski tygodnik lekarski (Warsaw, Poland : 1960)》1989,44(15-16):354-357
The authors compared the results of 20 emergency and 100 elective varicosclerotisations with rigid esophagoscope and the same number of obliterations with the use of esophagofiberoscope. Haemorrhage was stopped in 90% of patients injected through the rigid esophagoscope and in 80% of patients in whom esophagofiberoscope was used. Hospital mortality rate in patients with bleeding esophageal warices was 25% in both groups. Complications were seen in 4.2% of procedures carried out with the rigid esophagoscope, and 5.8% of obliterations with esophagofiberoscope. The authors recommend rigid esophagoscope for emergency sclerotherapy and for the initial 2-3 series of injections in patients with large varices. Esophagofiberoscope is prefered in case of repeated, elective varicosclerotisations, first injections and recurrence of esophageal varices following obliterative therapy. 相似文献
77.
A mild and efficient one-step method of thiophosphorylation was devised for acid-sensitive nucleosides. The procedure is based on thiophosphorylation of nucleoside magnesium alkoxide by 2-chloro-2-thio-1,3,2-dioxaphospholane. The utility and efficiency of this method combined with deprotection of the resulting cyclic triester were demonstrated by its application to the synthesis of both adenosine 3'- and 5'-thiophosphates. The procedure does not require protection of the exocyclic amino group and can be successfully used for the thiophosphorylation of nucleosides that are unusually sensitive to depurination. 相似文献
78.
The chloroplast peripheral reticulum (PR) is a structure of unknown function. Some authors postulated that it is a characteristic feature of C4 plants, although it was reported from C3 species as well. It is unknown whether the occurrence of PR follows a phylogenetic (it is found in clades containing C4 species, regardless of the photosynthetic type) or functional (photosynthetic pathway dependent) pattern. Here, we present a phylogenetically controlled analysis of the occurrence, form and functional aspects of PR in grasses. The occurrence of the PR follows a functional and not a phylogenetic pattern. Its most elaborated form (PR type I) is a unique feature of C4 species. Although PR was found in some of the studied C3 grasses, it was always less developed than PR in the chloroplasts of Kranz mesophyll cells of C4 species. The size of PR in C4 plants was found to increase when the plants were grown under low light intensity. Additional observations, such as a negative correlation between PR size and chloroplast surface and PR occurrence in vicinity of mitochondria or plasmodesmata, suggest that PR may play some role in C4 metabolism. 相似文献
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