Disease relevance of R Factors

• Cells of Escherichia coli harboring R factors that determine kanamycin resistance were infected with phage lambda, and lambdakan transducing lines were obtained [1].
• Retrovirus resistance factors Ref1 and Lv1 are species-specific variants of TRIM5alpha [2].
• The structures of the long-chain mannitol 2-dehydrogenase (54 kDa) from Pseudomonas fluorescens in a binary complex with NAD(+) and ternary complex with NAD(+) and d-mannitol have been determined to resolutions of 1.7 and 1.8 A and R-factors of 0.171 and 0.176, respectively [3].
• We studied 21 strains of amikacin-resistant Serratia marcescens from three different U.S. cities, Twenty of the 21 strains contained conjugative R plasmids mediating gentamicin and tobramycin resistance [4].
• New tetracycline resistance determinant on R plasmids from Vibrio anguillarum [5].

High impact information on R Factors

• Primary structure of a chloramphenicol acetyltransferase specified by R plasmids [6].
• The chloramphenicol resistance determined by Tn9, and by various other R plasmids, is due to the synthesis of the enzyme chloramphenicol acetyl transferase (CAT) [7].
• Considerable variations in resistance factors were noted for each cell subline as the amsacrine substituents were altered [8].
• R factors mediating gentamicin resistance were demonstrated in 34 of 36 strains [9].
• The structures were refined to R factors of 23% and 24% for the Cd(2+) and Zn(2+) complexes, respectively [10].

Chemical compound and disease context of R Factors

• Structures of adenylosuccinate synthetase from Escherichia coli complexed with guanosine-5'-(beta,gamma-imido) triphosphate and guanosine-5'-(beta,gamma-methylene)triphosphate in the presence and the absence of Mg2+ have been refined to R-factors below 0.2 against data to a nominal resolution of 2.7 A [11].
• Identification of tetracycline-resistant R-plasmids in Streptococcus agalactiae (group B) [12].
• Two strains of trimethoprim-resistant Shigella sonnei bearing R plasmids pBH600 and pBH700 each elaborated a dihydrofolate reductase (DHFR) and were moderately resistant to trimethoprim (minimum inhibitory concentrations, 128 and 256 micrograms/ml, respectively) [13].
• Most strains of Pseudomonas aeruginosa are significantly more resistant, even in the absence of R plasmids, to many antimicrobial agents, including beta-lactams, tetracycline, chloramphenicol, and fluoroquinolones, than most other gram-negative rods [14].
• Identification of R plasmids mediating gentamicin resistance from Escherichia coli strains in Japan [15].

Biological context of R Factors

• The R-plasmids from the transconjugants that transferred resistance to ampicillin exhibited different restriction fragment length polymorphism patterns, and a bla(TEM-1) probe was hybridized with the different fragments [16].
• Quantitative correlation between penicillin resistance and beta-lactamase activity specified by the R plasmids R1, R1 bla-45, and RP1 in Escherichia coli K-12 [17].
• In conclusion, our data provide evidence that CD40 may regulate cell death in non-hematopoietic cells in a dual fashion: the decision upon apoptosis or survival of a CD40-activated cell seems to depend on its ability to up-regulate resistance factors [18].
• The recombinant plasmids pJIR45 and pJIR97 contain the chloramphenicol resistance determinants derived from the Clostridium perfringens R plasmids pIP401 and pJIR27, respectively [19].
• Antiserum against an oxacillin-hydrolyzing penicillinase of Aeromonas hydrophila did not show immunochemical cross-reaction with four oxacillin-hydrolyzing penicillinases mediated by R plasmids [20].

Anatomical context of R Factors

• The three-dimensional structure of medium-chain acyl-CoA dehydrogenase from pig mitochondria in the native form and that of a complex of the enzyme and a substrate (product) have been solved and refined by x-ray crystallographic methods at 2.4-A resolution to R factors of 0.172 and 0.173, respectively [21].
• The structures of the native fructose-1,6-bisphosphatase (Fru-1,6-Pase), from pig kidney cortex, and its fructose 2,6-bisphosphate (Fru-2,6-P2) complexes have been refined to 2.8 A resolution to R-factors of 0.194 and 0.188, respectively [22].
• Trimethoprim R plasmids isolated during long-term treatment of urinary tract infection with co-trimoxazole [23].
• In the present study the two methods were directly compared in single-cell suspensions of three variants of the human breast carcinoma cell line MCF7: sensitive MCF7/WT, doxorubicin-selected MCF7/AdrR, and MDR1-gene-transfected MCF7/BC19 cells with doxorubicin resistance factors of 1, 192, and 14, respectively [24].

Associations of R Factors with chemical compounds

• The present models have been refined to 2.8 A and 2.2 A, with crystallographic R factors of 24.1% and 23.3% for the dT and Ganciclovir complexes respectively, without the inclusion of any solvent molecules [25].
• Cancer patients are significantly depleted of ascorbic acid, and in our opinion this demonstrable biochemical characteristic indicates a substantially increased requirement and utilization of this substance to potentiate these various host resistance factors [26].
• In studies with the COV413B cells and their cis-DDP-resistant counterpart COV413B-PtR, immunologically detected adduct levels again correlated closely with resistance factors (correlation coefficient = 0.97) [27].
• Two distinct types of trimethoprim-resistant dihydrofolate reductase specified by R-plasmids of different compatibility groups [28].
• The crystal structures of xanthan lyase and its complex with the product (pyruvylated mannose) were refined at 2.3 and 2.4 A resolution with final R-factors of 17.5 and 16.9%, respectively [29].

Gene context of R Factors

• PancTu I cells express the complement resistance factors CD46, CD55, and CD59, as we demonstrated by immunostaining, an observation that may explain the lack of cytotoxicity of the CA19-9-CVF conjugate [30].
• In contrast, MRP1-overexpressing cells, both drug selected and MRP1 transfected, are clearly resistant to IL-4 toxin with resistance factors of 4.3 to 8 [31].
• Resistance factors for TS inhibitors were: 2.4 and 0.4 for 5-fluorouracil (5FU), 18.8 and 8.8 for ZD1694, 17 and 0.7 for AG337, and 40 and 8.3 for BW1843U89 in SW-1573/2R160 and SW-1573/2R120, respectively [32].
• The structures of TARC have been solved by molecular replacement in two space groups, triclinic (P1) and tetragonal (P4(1)), and refined to resolutions of 1.72 and 2.1 A, respectively, with R factors of 19.8% (R(free) = 24.1%) and 19.8% (R(free) = 27.7%), respectively [33].
• Frequent expression of complement resistance factors CD46, CD55, and CD59 on gastrointestinal cancer cells limits the therapeutic potential of monoclonal antibody 17-1A [34].

Analytical, diagnostic and therapeutic context of R Factors

• Moreover, three different complexes of glucose-1-phosphate thymidylyltransferase (co-crystallized with dTDP, with dTMP and glucose-1-phosphate, with d-thymidine and glucose-1-phosphate) have been analysed by X-ray crystallography, in the 1.9-2.3 A resolution range (R-factors of 17.3-17.5 %) [35].
• By heteroduplex analysis the 30-Mdal plasmid was found to contain the entire ampicillin translocation DNA segment (TnA) found on R factors of enteric origin [36].
• Pulsed-field gel electrophoresis and restriction enzyme digestion analysis of R plasmids carrying these genes revealed different restriction profiles and sizes, indicating a dissemination of the gentamicin resistance genes through mobile molecular elements [37].
• Restriction endonuclease mapping and DNA hybridization revealed that these R plasmids were related to RSF1010 from Salmonella panama, which also confers resistance to streptomycin and sulfonamides [38].
• Because resistance to quinolones is not mediated by R-factors, it is recommended to select them as first choice in the treatment of patients with complicated UTI with indwelling catheters or nephrostomy tubes, and in patients with discharging ears in order to limit the spread of resistant strains in the hospital environment and in the community [39].

References