Results 271 to 280 of about 17,031,818 (292)

R Factors for Aminoglycoside Antibiotics

Journal of Infectious Diseases, 1969
The definition of R factors by Japanese scientists 10 years ago opened a new chapter in the saga of antibiotic resistance among enteric bacteria [1]. This package of extrachromosomal genes, comprised of the resistance determinants, which mediate resistance to a variety of environmental hazards, and the resistance transfer factors (RTF), which mediate ...
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Cancer and the unavoidable R factor

Science, 2017
Cancer Etiology Most textbooks attribute cancer-causing mutations to two major sources: inherited and environmental factors. A recent study highlighted the prominent role in cancer of replicative (R) mutations that arise from a third source: unavoidable errors associated with DNA replication. Tomasetti et al.
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Independence number, connectivity, and r‐factors

Journal of Graph Theory, 1989
AbstractWe show that if r ⩾ 1 is an odd integer and G is a graph with |V(G)| even such that k(G) ⩾ (r + 1)2/2 and (r + 1)2α(G) ⩽ 4rk(G), then G has an r‐factor; if r ⩾ 2 is even and G is a graph with k(G) ⩾ r(r + 2)/2 and (r + 2)α(G) ⩽ 4k(G), then G has an r‐factor (where k(G) and α(G) denote the connectivity and the independence number of G ...
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The Evolution of R Factor

New England Journal of Medicine, 1970
Abstract Although the therapeutic use of antibiotics favors the selection of bacteria that contain R factor, it does not necessarily follow that man-made antibiotics have induced the evolution of R factor. We have obtained evidence that R factor evolved before the advent of the antibiotic era.
C E, Davis, J, Anandan
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A reexamination of the WAIS—R factor structure.

Psychological Assessment: A Journal of Consulting and Clinical Psychology, 1990
We performed a series of restricted factor analyses on the 9 cohorts of the WAIS-R standardization sample in an effort to investigate the structure of this instrument. Several indices of fit were used including (a) the likelihood ratio test statistic, chisquare; (b) the LISREL Goodness of Fit Index; (c) the normed-fit index, with both a null and ...
Niels G. Waller, Irwin D. Waldman
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Inhibition of R-factor transfer by levallorphan

Biochemical and Biophysical Research Communications, 1971
Abstract The transfer of an R-factor from Proteus Rettgeri to Escherichia coli W 677 was strongly inhibited by levallorphan at concentrations which do not affect growth of either the donor or the recipient cells. The effect is not due to the transfer of the episom itself but to inhibition of mating-pair formation.
R, Löser, P L, Boquet, R, Röschenthaler   +2 more
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Role of R Factor and Bacterial Host in Sulfonamide Resistance Mediated by R Factor in Escherichia coli

Journal of Infectious Diseases, 1971
antimicrobial agents. Separate genetic determinants, grouped in various patterns on individual R factors, specify resistance to sulfonamides, penicillins and cephalosporins, chloramphenicol, tetracyclines, the kanamycin-neomycin group of antibiotics, and streptomycin, together with some related aminoglycoside antibiotics [1-3].
S A, Kabins, M V, Panse, S, Cohen
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R Factors

Journal of Infectious Diseases, 1969
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An R Factor Defects to Our Side

New England Journal of Medicine, 1972
IN the battle between antibiotics and gram-negative bacilli much of the enemy's strategy is dictated by twisted circles of DNA known as R factors. R factors replicate autonomously within the cell as extrachromosomal genetic elements that can be transferred to other strains on contact by conjugation.
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R Factors

Science, 1976
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