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Biomedical subjects

R L Metcalf

Publications and source records attributed to R L Metcalf.

At least 73 records · Page 4Linked to original sources
PubMed1967

Salicylanilides: a new group of active uncouplers of oxidative phosphorylation.

Investigations using housefly mitochondria revealed several salicylanilide derivatives as the most effective uncoupling agents of oxidative phosphorylation reported so far. Even greater inhibition of the associated P(i)-adenosine triphosphate exchange was shown with these compounds in both housefly and rat-liver mitochondria, and close similarity was observed between the two types of organelles.

Adenosine Triphosphatases↗
PubMed1966

Carbamate-resistance in mosquitos. Selection of Culex pipiens fatigans Wiedemann (=C. quinquefasciatus Say) for resistance to Baygon.

The authors investigated the rate of development and other characteristics of Baygon-resistance in Culex pipiens fatigans (=C. quinquefasciatus) recently colonized from Southern California. Selective pressure against the larvae (strain L) for 35 generations resulted in 25.4-fold resistance in larvae, but only 3-fold and 4.8-fold resistance in adults, as determined by contact and topical application, respectively. Conversely, selective pressure on adults (strain A) for 24 generations resulted in 8.4-fold (contact) and 5.3-fold (topical) resistance in adults, but only 2.7-fold resistance in larvae. About 10% of strain A adults survived 1-hour contact exposure even when the concentration of Baygon was increased 100-fold. This was not due to enhanced phototropism in this stage. Larvae of strain L metabolized (14)C-labelled Baygon at a rate 2.5-fold greater than the non-selected strain. Cross-resistance in strain L to carbamates closely related to Baygon was high, but was extremely low to remotely related carbamates.The authors consider the relatively slow rate of development of resistance to Baygon, the reduced expressivity of the resistance character in adults, and its specificity for the selective agent and for closely related carbamates to be encouraging indications as to the usefulness of this class of compounds for mosquito control.

Carbamates↗
PubMed1965

Toxicity of certain new compounds to insecticide-resistant houseflies.

Houseflies in poultry ranches in certain areas of California are now resistant to most insecticides licensed for use in these establishments, and this resistance problem appears likely to spread to other areas in the future. The authors have therefore studied the contact and oral toxicity of 19 new compounds that have shown interesting properties against resistant flies. These compounds were selected from among several hundred submitted by various laboratories for evaluation under a co-operative programme sponsored by the World Health Organization.Five compounds were found to be as toxic to three insecticide-resistant strains as to a susceptible strain, and showed strikingly steep log-dosage/probit mortality lines against the resistant strains. The authors suggest that these compounds be further studied for fly control in field trials.

California↗
PubMedDate not supplied

DDT and selected analogues as microsomal oxidase inducers in the mouse.

Sixteen DDT-type compounds were tested in the mouse for their ability to induce hepatic microsomal enzymes and cytochrome P-450. Results suggested three categories of inducers: (a) inducers which are metabolized to inducers, (b) temporary inducers which are metabolized to noninducers, and (c) noninducers. Freedom from inductive properties is suggested as a parameter for new microcontaminant chemicals.

Animals↗