Michael H. Briggs

Effects of steroid pharmaceuticals on plasma zinc.

ORAL contraceptives have been found to cause large changes in the levels of copper and iron in the blood1. Their effects on the level of plasma zinc, however, are uncertain, for although in one case it was reported that the level increased2, in another significant decreases were found3. Apart from testosterone propionate, which was found to increase the level of plasma zinc4, other widely used steroid pharmaceuticals have not been investigated. We therefore undertook to determine the effects of such substances, including oral contraceptives, on the plasma zinc of healthy human subjects.

Relationship between Locomotory Habits and Enzyme Concentration in Insects

The activity of alpha-glycerol phosphate dehydrogenase has been measured in muscles from four insect species. In flying insects the enzyme activity is much greater per unit weight for flight muscles than for leg muscles. The results indicate a direct relationship between muscle levels of the enzyme and habitual mode of locomotion.

Some aspects of the metabolism of ascorbic acid in insects.

Abstract 1. 1. The concentration of free and bound ascorbic acid, and of dehydroascorbic acid, is reported for five insect species: Musca domestica, Cutelia sedilotti, Dasycolletes hirtipes (Hudson), Melampsalata, cingulata , and Apis mellifera . 2. 2. The tissue distribution of reducing compounds is described. 3. 3. Bound hydroxyproline was found in all five species, but free hydroxyproline was detected only in Apis and Dasycolettes . 4. 4. The oxidation of l -tyrosine by Cutelia homogenates was activated by ascorbic acid and the other cofactor requirements of this system were determined. 5. 5. Ascorbate oxidation by homogenates of the two Hymenoptera occurred best at pH 5·5. 6. 6. Musca homogenates were shown to synthesize ascorbic acid from a variety of hexoses.