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871.
Some preliminary data regarding the test of penetration and proliferation of BHK and HeLa cells biocompatibility to a three dimensional stroma saturated with phosphorous and calcium salts (a biomaterial replacing bone) are presented. These data suggest that the analysed biomaterial might be used in surgical practices of prosthesis appliance on interfaces of fractured bone. 相似文献
872.
Interaction of netropsin and distamycin with deoxyribonucleic acid: electric dichroism study 总被引:13,自引:0,他引:13
We report dichroism and equilibrium binding studies of netropsin (Net) and distamycin A3 (Dist) binding to deoxyribonucleic acid (DNA). We show that at low degrees of binding (r) to calf thymus DNA, Net induces a considerable increase in the apparent DNA length (14 A/drug molecule bound), closely analogous to the results reported earlier for Dist. In addition, we show that chicken erythrocyte DNA shows length changes similar to those of calf thymus DNA upon distamycin binding. DNA length reaches a maximum at 1 bound drug/20-30 base pairs and then decreases to its initial value by r = 0.1. This effect is not seen for two other DNAs with nearly identical A + T base pair content and may therefore arise from the details of base sequence or base modification in eukaryotic DNA. We also show that Dist binding to calf thymus DNA at low r values is positively cooperative and shows a DNA affinity which is primarily nonionic. We demonstrate that independent of the DNA to which they are bound, the Net and Dist transition moments are inclined by 43 +/- 3 degrees from the helix axis, consistent with the idea that both drugs bind inside and parallel to the DNA small groove. From dichroism measurements, we show that the conformational change induced in calf thymus DNA by Dist does not kink or bend the helix and does not substantially alter the average inclination of the bases. Finally, we outline a statistical mechanical theory for calculation of binding isotherms when binding is coupled to a DNA structural change. 相似文献
873.
N. KINGSTON JAMIE K. MORTON ROBERT DIETERICH 《The Journal of eukaryotic microbiology》1982,29(4):588-591
Twenty-nine (64.4%) of 45 reindeer, Rangifer tarandus, examined over a two-year period were infected with trypanosomes. Trypomastigotes and dividing epimastigotes were found in the blood of fawns, cows, and bulls. Morphometric analysis of bloodstream trypomastigotes from reindeer and comparison of these parasites with similar stages of trypanosomes from elk, mule deer, and white-tailed deer from the contiguous United States proved them conspecific; the trypanosomes from these members of the Cervidae are identified as Trypanosoma cervi Kingston & Morton, 1975. This is the first report of trypanosomes from reindeer. No pathogenic effects are known to be caused by these parasites. 相似文献
874.
A simplified method of manual calculation for inbreeding coefficient (and/or relationship) from complicated pedigree tables presented in a nongraphic mode is offered. The method is based on the use of positional dual codes of ancestors in which all genealogical links of the proband are reflected. 相似文献
875.
N Durán Y Makita L H Innocentini 《Biochemical and biophysical research communications》1979,88(2):642-648
The presence of enzymically generated triplet acetone in red cells and energy transfer to eosin, rose bengal and 9,10-dibromoanthracene-2-sulfonate was indicate by: (1) product distribution; (2) KET τo, similar to the 2-methylpropanal/peroxidase/O2 system; (3) correlation between hemolysis, oxygen uptake and photon emission; (4) membrane protection by energy acceptors, and (5) by comparison of the 2-methylpropanal/peroxidase/O2 system with 2-methylpropanal/red cells/membranes/O2 and 2-methylpropanal/acid extractable protein from red cells membrane/O2 systems, which have a high peroxidase activity.This is the first report of a biological system producing a photohemolysis effect in the dark. 相似文献
876.
V. S. Kurbanismailov O. A. Omarov G. B. Ragimkhanov M. Kh. Gadzhiev M. G. Bairkhanova A. J. Kattaa 《Plasma Physics Reports》2011,37(13):1166-1172
The experimental results on the formation and development of initial stages of an impulse breakdown in atmospheric-pressure
argon at townsend and streamer breakdown mechanisms for different initial conditions are presented. A streamer channel is
shown to be initiated by bright luminescence formed at the point of critical avalanche amplification at different distances
from the cathode depending on overvoltage. Prebreakdown currents are experimentally measured for the townsend and streamer
breakdown mechanisms and peculiarities of spark channel formation for these mechanisms are studied. 相似文献
877.
Merkel cell tumor: diagnosis, prognosis, and management 总被引:2,自引:0,他引:2
The histologic features of the Merkel cell and the pathologic characteristics of the Merkel cell tumor are described. From a literature review, 68 cases are examined; 23 cases that have been followed up accurately are presented from the Mayo Clinic. A representative case is used to demonstrate the problems of diagnosis and suggested treatment. The latter should be wide local resection with removal of nodal metastases if present. When indicated, this should be followed up with radiation therapy. Chemotherapy is of little or no value. Survival rates are presented. 相似文献
878.
879.
The paper analyzes humus profiles of mountain-chestnut soils of a complex catena situated within the Khemchik dry-steppe area
of the Central Tuva Depression. The study has shown that humus profile characteristics are determined by both slope aspects
and position in the catena. Humus profiles imprint all environmental changes of soil formation and functioning even if these
changes are not expressed in soil morphology. The materials obtained during the study may serve as basis for long-term monitoring
of slope soil behavior and for revealing local soil variability in changing environment. 相似文献
880.
R M Dixon B T Golding S Mwesigye-Kibende D N Ramakrishna Rao 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1985,311(1152):531-544
The vitamin B12 coenzyme adenosylcobalamin assists the enzymic catalysis of molecular rearrangements of the type (formula; see text) in which the migrating group X can be OH, NH2 or a suitable substituted carbon atom such as C(=CH2)CO2H. This paper discusses evidence for the participation of organic radicals as intermediates in these reactions. Theoretical and model studies supporting the intermediacy of radicals in the reactions catalysed by the enzymes diol dehydratase and alpha-methyleneglutarate mutase are described. For the model studies, alkyl radicals, alkylcobaloximes (alkyl represents, for example, ethoxycarbonyl substituted, but-3-enyl and cyclopropylmethyl) and also dihydroxyalkylcobalamins have been investigated. The Co-C alpha-C beta angle of 125 degrees in adenosylcobalamin is shown to be an 'especial' angle by analysis of the crystal structures of R- and S-2,3-dihydroxypropylcobalamin. 相似文献