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Several lines of evidence suggest that insect repellent molecules reduce mosquito-host contacts by interacting with odorants and odorant receptors (ORs), thereby ultimately affecting olfactory-driven behaviours. We describe the molecular effects of 10 insect repellents and a pyrethroid insecticide with known repellent activity on two highly specific Aedes aegypti (Diptera: Culicidae) ORs, AaOR2 + AaOR7 and AaOR8 + AaOR7, exquisitely sensitive to key mosquito attractants indole and (R)-(-)-1-octen-3-ol, expressed in oocytes of Xenopus (Anura: Pipidae). Our study demonstrates that insect repellents can both inhibit odorant-evoked currents mediated by ORs and independently elicit currents in the absence of odorants. All of the repellents had effects on one or both ORs; most of these compounds were selective inhibitors and showed a high degree of specificity in their capacity to activate the two ORs. These results show that a range of insect repellents belonging to structurally diverse chemical classes modulate the function of mosquito ORs through multiple molecular mechanisms.

A total of 300 children aged five years and under, referred for routine EEG investigations, were included in this study. It was possible to obtain recordings during natural sleep in 250 of the 300 children, using stick-on electrodes. Of the 250 with natural-sleep recordings, 110 children had normal records both awake and asleep. In 73 cases the awake record was normal but the asleep record showed abnormalities, the most common being spike discharges (60 children). Of these 60 children, 52 had a history suggestive of epilepsy or of febrile convulsions. A further 27 children had recordings which were equally abnormal awake and asleep, and 37 showed abnormalities while awake but greater abnormalities while asleep. It is concluded that useful additional information can be obtained from the EEG if young children are encouraged to sleep naturally during the recording, and that this can be done without sedation, even in a busy, routine EEG department.