Subject synthetic steroids

The normal subject may retain sodium and water during steroid therapy, although the synthetic steroid ana-... 

Q10 Cortisol secretion is normally suppressed by exogenous glucocortocoids. In a normal subject, administration of the synthetic steroid dexamethasone produces a rapid feedback inhibition of CRF and ACTH, which in turn suppresses or diminishes cortisol production to a low level. In Cushing s disease little or no suppression will occur. 

Many chemists, working in the field of steroids, have been interested in the subject of chemical structure, biological activity relationship. As the number of synthetic steroids increases at an ever-growing rate, more and more theories are put forward to explain their mode of action. 

Natural and synthetic steroids have become a major subject of worldwide growing concern because these compounds may interfere with the normal reproduction of human, livestock, and wildlife. 

In the early 1930 s, when the prime research aim was the commercial synthesis of the sex hormones (whose structures had just been elucidated), the principal raw material available was cholesterol extracted from the spinal cord or brain of cattle or from sheep wool grease. This sterol (as its 3-acetate 5,6-dibromide) was subjected to a rather drastic chromic acid oxidation, which produced a variety of acidic, ketonic and hydroxylated products derived mainly by attack on the alkyl side-chain. The principal ketonic material, 3j -hydroxyandrost-5-en-17-one, was obtained in yields of only about 7% another useful ketone, 3 -hydroxypregn-5-en-20-one (pregnenolone) was obtained in much lower yield. The chief acidic product was 3j -hydroxy-androst-5-ene-17j -carboxylic acid. All three of these materials were then further converted by various chemical transformations into steroid hormones and synthetic analogs ... 

Retinoids are a family of naturally occurring and synthetic analogues of vitamin A. The skin of subjects deficient in vitamin A becomes hyperplastic and keratotic (phrynoderma, or toad skin). While natural vitamin A is occasionally employed therapeutically, synthetic retinoids are more effective and represent a major advance in dermatological pharmacotherapy. Retinoids have myriad effects on cellular differentiation and proliferation it is likely that nuclear retinoic acid receptors mediate these effects by activating gene expression in a manner analogous to receptors for steroid hormones and thyroid hormones. Despite a common mechanism of action, however, retinoids vary widely in their physiological effects. 

The strong interactions between certain bivalent cations and the highly ordered polynucleotides such as DNA, certain synthetic duplex homo- and heteropolymers, and s-RNA have been the subject of much current interest. With this idea in mind, it is interesting to note that the steroidal diamine cyclobuxine-D (242) was shown to exert a profound effect on the stability of helical polynucleotides (DNA, s-RNA, and dAT dAT). The effect is biphasic in the sense that at low concentrations of the agent there is stabilisation of the native conformation, while at higher concentrations there is stabilisation of the denatured conformation. 

Steroids. Subjects on ethinylestradiol-norethisterone contraceptive pills had significantly lower Hb Aj levels than women using barrier or antiestrogen techniques (Ol). This is in harmony with observations that synthetic estrogens lower plasma glucose, possibly via an effect on the portal insulin glucagon ratio. 

A great deal has been published in recent years on the preparation and synthetic use of enamines and there have been a number of excellent reviews on the subject [142, 143, 144, 145]. The use of enamines as protective groups has been more limited and restricted to the steroid field where their preferential formation from aldehydes [146] and from a, -unsaturated ketone groups [147, 148, 149, 150, 151] has been exploited in particular. 

There are a number of ways in which TLC can be combined to advantage with GLC. The spots obtained from TLC may be eluted, concentrated, and then subjected to GLC analysis. This method has been used in the analyses of lipids, steroids, alcohols, fatty acids, esters, glycerides, hydrocarbons, essential oils, and many other natural and synthetic organic compounds. Methyl esters of fatty acids are first separated on silver-nitrate-impregnated silica gel... 

There are examples of the uncatalyzed exchange with HHO at the a-positions of steroidal ketones . The ketone functions were immediately subjected to synthetic transformations in order to prevent tritium loss by back-exchange. The C2 positions of imidazole-containing pharmaceuticals have been similarly exchanged in this case, the half-time for loss of the tritium label was determined to be 2.4 days at 37 °C and pH 7, adequate for the intended study. This figure is similar to that measured for [imidazole-2- H]histidine, namely 2.8 days at 37 °C and pH 8.2. 

Selective drugs are usually synthetic and of low molecular weight (< 500). Sometimes, however, they are of natural origin, but used outside their natural context (examples being, alkaloids, antibiotics and overdoses of steroids). Immunochemicals, as in vaccines and sera, are separated from our subject by their enormous molecular weight. 

---