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Biomedical subjects

A Fontan

Publications and source records attributed to A Fontan.

At least 19 recordsLinked to original sources
PubMed1990

The biochemical basis of tolerance to malathion in Rhodnius prolixus.

1. LC50 of malathion, fenitrothion and lindane were determined in R. prolixus and T. infestans. R. prolixus was shown to be tolerant to malathion. 2. The penetration rate of (14C)-malathion into R. prolixus and T. infestans was similar. 3. Acetylcholinesterase from R. prolixus heads was 3.3-fold less sensitive to inhibition by malaoxon than the similar enzyme of T. infestans. 4. R. prolixus showed more activity of GSH-S-transferases against DCNB than T. infestans. 5. The in vitro degradation of (14C)-malathion demonstrated that R. prolixus is more active than T. infestans in carboxyester splitting to give alpha and beta monoacids. 6. The synergism of TPP and TOCP on malathion toxicity was higher in R. prolixus than in T. infestans. 7. Esterase activity against alpha and beta naphthyl acetates proved to be much lower in R. prolixus homogenates than in T. infestans homogenates. An inverse result was observed when PTA was the substrate.

Acetylcholinesterase↗
PubMed1984

Integumental esteratic activity in Triatoma infestans and its contribution to the degradation of organophosphorus insecticides.

Esteratic activity was found in the integument of adult Triatoma infestans, principally located in the epidermis. Specific activity was on average 29.3 nM phenylthioacetate/hr per anatomical unit. Esteratic activity depends on the insect's age and its starvation state. A dramatic increase was observed 1 week after moulting followed by a slight decay as a function of the age. A significant decrease of the activity was observed with a longer fasting time. Integumental esterases were characterized as carboxylesterases, butyrylcholinesterases and aryl plus acetylesterases by using eserine and paraoxon as inhibitors and acetylthiocholine, butyrylthiocholine and phenylthioacetate as substrates. Epidermis homogenates were able to hydrolyse OP insecticides when incubated in vitro. Hydrolysis of the carboxyester linkage by malathion was established and cleavage of the P-S-C bond by parathion.

Animals↗