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Biomedical subjects

T W Walker

Publications and source records attributed to T W Walker.

18 recordsLinked to original sources
PubMed1996

Field evaluation of arthropod repellents, deet and a piperidine compound, AI3-37220, against Anopheles funestus and Anopheles arabiensis in western Kenya.

A field evaluation of the repellents N,N-diethyl-3-methylbenzamide (deet) and 1-(3-cyclohexen-1-yl-carbonyl)-2-methylpiperidine (AI3-37220, a piperidine compound) was conducted against Anopheles funestus and An. arabiensis in Kenya. Both repellents provided significantly more protection (P < 0.001) than the ethanol control. AI3-37220 was significantly more effective (P < 0.001) than deet in repelling both species of mosquitoes. After 9 h, 0.1 mg/cm2 of AI3-37220 provided 89.8% and 71.1% protection against An. arabiensis and An. funestus, respectively. Deet provided > 80% protection for only 3 h, and protection rapidly decreased after this time to 60.2% and 35.1% for An. arabiensis and An. funestus, respectively, after 9 h. Anopheles funestus was significantly less sensitive (P < 0.001) to both repellents than An. arabiensis. The results of this study indicate that AI3-37220 is more effective than deet in repelling anopheline mosquitoes in western Kenya.

Adult↗
PubMed1995

Response of wild Anopheles funestus to repellent-protected volunteers is unaffected by malaria infection of the vector.

A field experiment was conducted to compare the biting behavior of Plasmodium falciparum-infected and uninfected Anopheles on humans using mosquito repellents. Repellent formulations (5% [wt/vol] N,N-diethyl-3-methylbenzamide [deet] or 5% [wt/vol] AI3-37220, a piperidine compound, both in 100% ethanol, or 100% ethanol alone [as a control]) were applied to the lower legs of 3 collectors in each of 4 houses. Collectors caught mosquitoes over 6 collection nights. Mosquitoes were collected into vials after they initiated probing on the leg of a collector. Infected females made up the same proportion of the Anopheles funestus populations biting either repellent-protected or unprotected individuals. We conclude that repellent formulations are equally effective against Plasmodium-infected and uninfected An. funestus.

Animals↗
PubMed1985

Susceptibility of Romanomermis culicivorax (Nematoda: Mermithidae) postparasites to agrichemicals used in Louisiana rice production.

Susceptibility of Romanomermis culicivorax postparasites to riceland agrichemicals was evaluated during 1983. Nematode mortalities for all agrichemicals at 2 days posttreatment ranged from 0 to 11.4% with fentin hydroxide + urea responsible for the highest mortality. Fertilizers were significantly more toxic to nematodes at 2 and 25 days posttreatment than were insecticides. Carbofuran and methyl parathion produced less than 1% mortalities at 2 days and less than 5% mortalities at 25 days posttreatment. Approximately 80-84% of the surviving females exposed to insecticides as postparasites became gravid. Infectivity of the subsequent F1 generation preparasites resulted in greater than 92% parasitism in Culex quinquefasciatus larvae, except those produced by nematodes exposed to carbofuran (76.4%), 2,4-D (70.9%) and fentin hydroxide (67.4%).

Agriculture↗
PubMed1985

Establishment and recycling of Romanomermis culicivorax (Nematoda: Mermithidae) in Louisiana ricelands.

The postparasitic stage of Romanomermis culicivorax, applied at dosage rates of 0.025 and 0.05 g/m2, was able to establish, recycle and overwinter in a riceland habit in southern Louisiana. Percent parasitism ranged from 0 to 54.1% during the 22-month study. Parasitism of Psorophora columbiae larvae was significantly greater (P less than 0.05) along levee ditches than in the central portions of the fallow riceland plots on 3 of 4 sampling dates in 1983. As percent parasitism increased within the population of Ps. columbiae located in bioassay containers, the degree of superparasitism also increased.

Animals↗
PubMed1980

The influence of standards on health care delivery.

The standardization of medical products and devices is a topic which has recently spawned a large number of articles in various journals. Certain of these are highly informative, and others are not. Accordingly, it is time for the Canadian Standards Association (CSA) to place greater emphasis on the second of its responsibilities and to begin to provide the public with more basic information concerning standardization in the field of health care technology. In order to achieve this, CSA has prepared a series of articles which outline the goals and the major requirements of standards for various types of devices or installations. This is the first in that series, and is intended to provide information on what standards are and how they are intended to influence the health care delivery system.

Canada↗