W.A. Skinner

Bio: W.A. Skinner is an academic researcher from SRI International. The author has contributed to research in topics: Aedes aegypti & Vitamin E. The author has an hindex of 12, co-authored 38 publications receiving 468 citations.

The effect of various concentrations of tocopherols and tocopherol mixtures on the oxidative stability of a sample of lard.

Abstract: A comparison was made of α-, γ-, and δ-tocopherol at various concentrations and a mixture of these tocopherols representing the average tocopherol content of peanut oil on the oxidative stability of lard at 97C. Uptake of oxygen was used to indicate the length of the induction period. The antioxidant effectiveness of the tocopherols was found to increase in the order α, δ, γ. The antioxidant efficiency decreases with increasing concentrations of tocopherols such that addition of any single tocopherol above a concentration of 250 µg/g has little effect on oxidative stability. A mixture equivalent to that of an average peanut oil sample, containing 150 µg/g of α-tocopherol and 250 µg/g of γ-tocopherol and 15 µg/g of δ-tocopherol was found to be no more stable than one containing 250 µg/g of γ-tocopherol alone.

Factors that attract and repel mosquitoes in human skin.

Abstract: The aim of this research program is to find an orally active insect repellent. By carefully screening drugs at random—a formidable task whose success depends on chance rather than knowledge—such an agent could hopefully be found. We have chosen to look instead to nature for a solution of this problem. We assume that human and animal skin contains factors attractive to mosquitoes. Knowledge of these attractant factors should lead to methods of interruption as the basis of an ideal repellent. This report reviews our efforts to measure the relative attractiveness of individuals and identify the responsible agents. Search for the Unattractive Man Folklore indicates that some humans are never bitten by mosquitoes. In casual discussion, several lay and professional colleagues have informed us that they know of at least one such person. One must be certain that this is not lack of skin reactivity to the bite. Whenever possible, we

Molluscicidal Saponins of Phytolaccadodecandra: Lemmatoxin

Abstract: Lemmatoxin, one of the molluscicidal saponin components of the fruit of Phytolaccadodecandra (endod), has been found to be a derivative of oleanolic acid substituted in the 3 position with a branch...

The chemistry and antioxidant properties of tocopherols and tocotrienols

Abstract: This article is a review of the fundamental chemistry of the tocopherols and tocotrienols relevant to their antioxidant action. Despite the general agreement that α-tocopherol is the most efficient antioxidant and vitamin E homologuein vivo, there was always a considerable discrepancy in its “absolute” and “relative” antioxidant effectivenessin vitro, especially when compared to γ-tocopherol. Many chemical, physical, biochemical, physicochemical, and other factors seem responsible for the observed discrepancy between the relative antioxidant potencies of the tocopherolsin vivo andin vitro. This paper aims at highlighting some possible reasons for the observed differences between the tocopherols (α-, β-, γ-, and δ-) in relation to their interactions with the important chemical species involved in lipid peroxidation, specifically trace metal ions, singlet oxygen, nitrogen oxides, and antioxidant synergists. Although literature reports related to the chemistry of the tocotrienols are quite meager, they also were included in the discussion in virtue of their structural and functional resemblance to the tocopherols.

Comparative Efficacy of Insect Repellents against Mosquito Bites

Abstract: Background The worldwide threat of arthropod-transmitted diseases, with their associated morbidity and mortality, underscores the need for effective insect repellents. Multiple chemical, botanical, and "alternative" repellent products are marketed to consumers. We sought to determine which products available in the United States provide reliable and prolonged complete protection from mosquito bites. Methods We conducted studies involving 15 volunteers to test the relative efficacy of seven botanical insect repellents; four products containing N,N-diethyl-m-toluamide, now called N,N-diethyl-3-methylbenzamide (DEET); a repellent containing IR3535 (ethyl butylacetylaminopropionate); three repellent-impregnated wristbands; and a moisturizer that is commonly claimed to have repellent effects. These products were tested in a controlled laboratory environment in which the species of the mosquitoes, their age, their degree of hunger, the humidity, the temperature, and the light-dark cycle were all kept constant. Results DEET-based products provided complete protection for the longest duration. Higher concentrations of DEET provided longer-lasting protection. A formulation containing 23.8 percent DEET had a mean complete-protection time of 301.5 minutes. A soybean-oil-based repellent protected against mosquito bites for an average of 94.6 minutes. The IR3535-based repellent protected for an average of 22.9 minutes. All other botanical repellents we tested provided protection for a mean duration of less than 20 minutes. Repellent-impregnated wristbands offered no protection. Conclusions Currently available non-DEET repellents do not provide protection for durations similar to those of DEET-based repellents and cannot be relied on to provide prolonged protection in environments where mosquito-borne diseases are a substantial threat.

Mosquitoes and Mosquito Repellents: A Clinician's Guide

Abstract: This paper is intended to provide the clinician with the detailed and scientific information needed to advise patients who seek safe and effective ways of preventing mosquito bites.For this review,...