Michael Briggs

Glucocorticoid properties op progestogens

Abstract Single oral doses of progesterone, 17-hydroxyprogesterone acetate, medroxyprogesterone acetate, megestrol acetate, cortisol, or placebo were given to groups of fasting young men. Eosinophils, plasma glucose and corticosteroids were determined at hourly intervals for 8 hours. Maximum responses were compared between groups receiving different treatments. Progesterone is free of glucocorticoid properties in these tests, but medroxyprogesterone acetate has about 50% and megestrol acetate about 25% the eosinopenic and hyperglycemic activity of an equal weight of cortisol in the dose range tested. 17-hydroxyprogesterone acetate has no eosinopenic or hyperglycemic activity, but suppresses plasma corticosteroids similarly to equal weights of medroxyprogesterone acetate or megestrol acetate.

Lysosomal enzyme activation by steroid hormones in vivo

Abstract A series of 23 hormonal steroids and stilbestrol were examined for effects on β-glucuronidase activity of autolysed lysosome preparations from rat preputial glands. Compounds were administered into the saphenous vein of ovariectomized, or ovariectomized and adrenalectomized, animals 15 min before dissection of preputial glands. Lysosome-rich fractions of homogenates were obtained by differential centrifugation, and β-glucuronidase activity was measured before and after autolysis. Minimum doses of sex hormones required to induce statistically significant ( P For induction of lysosome labilization in this assay system, steroids required two oxygenic functions per molecule: one at C-3 and a second at either C-17 or C-20. Stabilization required a third group at C-11. Groups in these positions in the α-configuration were generally inactive; only β-substituents were associated with significant changes in β-glucuronidase activity.

Thiamine status and oral contraceptives.

Abstract Using in vitro Stimulation of erythrocyte transketolase by thiamine pyrophosphate as an index of thiamine status, measurements were conducted on 20 healthy young women immediately prior to beginning treatment with combined-type oral contraceptives, then again after 3 cycles. Erythrocyte transketolase became more unsaturated by its cofactor during treatment, indicating the induction of a mild thiamine hypovitaminosis by oral contraceptives.

ORAL CONTRACEPTIVES AND VITAMIN NUTRITION

This letter comments on an article by Sanpitak and Chayutimonkul (May 4) in which it was stressed based on studies of Thai women that oral contraceptives may be an unfavorable influence in populations with poor vitamin nutrition. To substantiate this finding data on women in the Republic of Zambia are presented. One group of women received the combined type of oral contraceptive. Another group received 150-mg medroxyprogesterone acetate (Depo-Provera) every 3 months by injection. A third group received no treatment. In the group taking oral contraceptives all the water-soluble vitamins were decreased (C B12 B6 and riboflavin) Vitamin-E was unchanged and plasma-retinol was increased. In the group taking Depo-Provera all vitamin levels were unchanged. The Depo-PRovera method of contraception is recommended for developing countries where vitamin nutrition may be poor.

BIOCHEMISTRY OF DRUGS

This chapter discusses pharmacodynamics, that is, the absorption, transport and, excretion of drugs. It also discusses the interaction of drugs with tissue metabolism and various chemical classes of pharmaceuticals. A major class of drugs are compounds that occur naturally in the human body and are given to correct deficiencies, either in the amounts of these constituents, or to increase tissue content for other reasons. Pharmaceuticals in this class include vitamins, hormones, bile salts, anti-sera, mineral salts, urea, oxygen and other gases, and so on. Many drugs-resembling compounds found in animal or plant tissues are manufactured synthetically rather than by extraction from tissues. The rapid entry of drugs into venous blood can occasionally lead to undesirable effects. If the osmolarity of the drug solution differs from that of blood, haemolysis or agglutination of erythrocytes may occur within the vein. Embolism can result if the drug precipitates out of solution in the vein or if a drug containing particulate matter is given accidentally by the intravenous route. Drugs may also damage the venous walls, particularly if given over a considerable length of time by i.v. infusion.

NATURAL ANTI-METABOLITES

This chapter discusses the range of anti-metabolites produced by animals, plants and microorganisms and the way in which these act on human metabolism or the metabolism of human pathogens. People are exposed to anti-metabolites from plant and animal foods, from purified preparations used as medicines, and from venomous animals such as snakes, spiders, and insects. There is also a small group of venomous plants that release toxins on contact with human skin. The basic principles of antimetabolic effects should be borne in mind. There is only a limited number of ways in which a toxic compound can produce its actions. The chapter discusses the biochemistry of microbial toxins and the different ways in which antibiotics act against pathogenic microorganisms. It also presents an account of microbial toxins acting on organisms causing human diseases.

METABOLISM OF FOREIGN COMPOUNDS

The human body is continually exposed to a wide range of substances that are not natural constituents of the body; indeed, many substances are the products of human industry and are never found in nature. The human digestive tract has evolved to cope with food components, while the internal organs possess limited capacities to metabolize and clear foreign compounds accidentally ingested with foods or released into the system by parasites. Pharmaceuticals of most types are foreign compounds, though a few contain substances normally present in the human body. This chapter discusses some commonly used pharmaceutical products, their actions, and their side-effects. Large numbers of foreign compounds may be derived from substances present in lipsticks, mascara, nail polish, soaps, perfumes, and skin creams. A high percentage of the lipstick applied to the lips is orally ingested, while the capacity of the skin to transfer topically applied compounds into the blood is frequently underestimated.

Chapter 4 – VENOMS

Publisher Summary This chapter discusses the classification and distribution of venomous snakes, insects, scorpions, and spiders. It also discusses the chemical composition of the venoms and venom apparatus of these organisms. In the animal kingdom, venomous animals can possess a wide variety of specialized apparatus for the production and administration of their poisons. Among vertebrates, the commonest type of venom apparatus is some modification to the teeth, jaws, and salivary glands, so that venom is administered by biting. A similar situation occurs in arachnids, though most venomous insects rely on modifications to their urinogenital tract and accessory organs, so that venom is administered by a sting. Other types of venomous structures include modified spines or specialized regions of an exoskeleton. Venomous plants are rare; however, mostly rely on delicate spines that rupture and penetrate on contact with skin so that the venom spreads on and in the epidermis.