Multiple resistance

Determination of Controlling Rate Factor The most important physical variables determining the controlhng dispersion factor are particle size and structure, flow rate, fluid- and solid-phase diffu-sivities, partition ratio, and fluid viscosity. When multiple resistances and axial dispersion can potentially affect the rate, the spreading of a concentration wave in a fixed bed can be represented approximately... 

Control of wound-rotor motors, as discussed, can be effected by adjusting the external secondaiy (rotor) resistance either in steps or continuously by liquid rheostat (this method is seldom used). Commonly when secondaiy resistance is varied to adjust speed or torque or to control acceleration, multiple resistance steps are used. These steps may be switched manually (typically a drum switch) or electrically by contac tor. 

Resistance may also be chromosomally mediated, t Multiple resistance genes may be carried on a transposon. 

Elicks BB, Baldocchi DD, Meyers TP, Hosker Jr RP, Matt DR. 1987. A preliminary multiple resistance routine for deriving deposition velocities from measured quantities. Water Air Soil Pollut 36 311-330. 

Hall, L., Topinka, K., Huffman, J., Davis, L. and Good, A. (2000). Pollen flow between herbicide-resistant Brassica napus is the cause of multiple-resistant B. napus volunteers. Weed Sci, 48, 688-694. 

Castiglioni S, Pomati E, Miller K et al (2008) Novel homologs of the multiple resistance regulator marA in antibiotic-contaminated environments. Water Res 42(16) 4271 280... 

Age of pig months No isolates Tetracycline resistance % Multiple resistance no ... 

Research on antibiotics which do not produce multiple resistance is, of course, desirable. Nisin appears to present just such a situation although its applications are narrow. Some feed additives are capable of "curing multiple resistance in enterics (50). This area deserves more research and emphasis. 

Because of the ultimate importance of vancomycin in the treatment of often fatal infections caused by multiple-resistant bacteria, extensive efforts have been directed toward the discovery of vancomycin derivatives with activity against these drug-resistant bacteria [89]. As a result of these efforts, several derivatives such as 41 (LY264826) have been found to be up to 500 times more effective than vancomycin itself. The most notable difference is the presence of another... 

Kiicken D., H-H. Feucht, and P-M. Kaulfers (2000). Association of qacE and qacEAl with multiple resistance to antibiotics and antiseptics in clinical isolates of gram-negative bacteria. FEMS Microbiology Letters 183 95-98. 

Pepeljnjak S, Kosalec I. 2004. Galangin expresses bactericidal activity against multiple-resistant bacteria MRSA, Enterococcus spp. and Pseudomonas aeruginosa. FEMS Microbiol Lett 240 111-116. 

Potential Risk from Cross-Resistance and Multiple-Resistance... 

Multiple-resistance is when more than one mechanism conferring resistance to herbicides in different chemical classes is active in an individual weed or population of weeds. Plants with multiple resistance may possess two or more distinct resistance mechanisms. Two grass species that display both cross- and multiple-resistance are rigid (or annual) ryegrass and blackgrass (Hall et al., 1994). 

Until the mid-1990s, multiple-resistance (i.e., resistance to more than one herbicide mode of action within the same biotype) had not been reported within North America. However, Foes et al. (1996) found a kochia biotype from western Illinois resistant to atrazine and several ALS-inhibiting herbicides. Lopez-Martinez et al. (1996) reported that a triazine-resistant Echinochloa species found in atrazine-treated com also showed cross-resistance to quinclorac. Clay and Underwood (1989) and Clay (1989) reported that one triazine-resistant biotype of American willowherb was also resistant to paraquat from a hop garden in the United Kingdom treated annually for 25 years with simazine and paraquat. 

Foes et al. (1998) reported that a common waterhemp biotype not controlled by triazine or ALS-inhibiting herbicides was isolated from a field in Illinois in the fall of 1996. Patzoldt et al. (2004, 2005) have reported on a tall waterhemp biotype in Illinois that has multiple resistance to ALS inhibitors, PPO inhibitors, and atrazine in the same plants. Maertens et al. (2004) reported a smooth pigweed biotype from southern Illinois confirming multiple resistance to both atrazine and ALS inhibitors. 

Hall, L.M., J.A.M. Holtum, and S.B. Powles (1994). Mechanisms responsible for cross resistance and multiple resistance. In S.B. Powles and J.A.M. Holtum, eds., Herbicide Resistance in Plants Biology and Biochemistry. Boca Raton, Florida CRC Press, pp. 243-261. 

Patzoldt, W.L., P.J. Tranel, and A.G. Hager (2005). A waterhemp (Amaranthus tuberculatus) biotype with multiple resistance across three herbicide sites of action. Weed Sci., 53 30-36. 

Sibony, M. and B. Rubin (2004). Molecular basis for diverse level of herbicide multiple-resistance in prostrate pigweed (Amaranthus blitoides). 4th International Weed Science Congress, p. 53, S15MT08P00. 

These biotypes show multiple resistance to X - modes of action (e.g., [g - 2] = 2 modes of action). 

Multiple-resistance mechanisms, defined as resistance due to more than one mode of action or class of herbicide, have been reported in several ALS-resistant weed biotypes - including false cleavers, wild oat, common waterhemp, kochia, rigid ryegrass in Australia (Powles and Matthews, 1992 Preston and Mallory-Smith, 2001), and wild radish (Walsh etal, 2004a). 

Diebold et al. (2003) concluded that multiple resistance in a Powell amaranth biotype in Ontario was due to the presence of altered target sites for triazine and imidazolinone herbicides. 

Hall et al. (1998) reported that an ALS-resistant biotype of false cleavers was cross-resistant to a broad range of ALS inhibitors, as well as to an auxin-type herbicide, quinclorac, which had never before been applied to these fields. A similar case of quinclorac multiple resistance in smooth crabgrass has been reported in California when plants were previously treated with ACCase herbicides. Data suggest a target site-based mechanism of resistance involving the accumulation of cyanide derived from stimulated ACC synthesis, which is a precursor of ethylene (Abdallah et al., 2004). 

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