Steroids difference

LLC systems for steroids. A GLC system therefore must achieve a number of theoretical plates approximately six times the number achieved in low-temperature LLC systems to achieve rough parity of performance in terms of the resolution of hydroxysteroids per system with currently available stationary phases, and twice the number for steroids differing by number of ketone groups. Such values can be achieved with expertly packed long GLC columns, Golay GLC columns, and with runs of 1-2 hours. Careful inspection of the literature will reveal that such conditions are not often used in published methods for steroids, despite the empirical recommendations of Horning and other pioneers in this field of technique. 

Recall How does the structure of steroids differ from that of the other lipids discussed in this chapter ... 

The choice of spacer depends on the drug to be delivered. The requirements for delivery of bronchodilators and steroids differ, and different devices may be required. 

The choice of spacer depends on the drug to be delivered. The requirements for delivery of bronchodilators and steroids differ, and different devices may be advisable. Simple containers or small-volume spacers may be used for bronchodilators, whereas optimized spacers are essential for delivery of inhaled steroids. Inexpensive but ineffective spacers may cause expensive loss of drug. 

In the apparently major pathway for the conversion of cholesterol into 5 -cholestane-3a,7a,12a-triol, the step following the formation of 7a-hydroxy-4-cholesten-3-one is a 12a-hydroxylation yielding 7a,12a-dihydroxy-4-cholesten-3-one (Fig. 1). The reaction is catalyzed by the microsomal fraction fortified with NADPH (15,37). The conversion of 5-cholestene-3, 7a-diol into 5-cholestene-3/5,7a,12a-triol, which is a reaction in another pathway for the formation of 5/5-cholestane-3a,7a,12a-triol, is also catalyzed by the microsomal fraction fortified with NADPH (30,37), as is the 12a-hydroxylation of 5/5-cholestane-3a,7a-diol and 7a-hydroxy-5)5-cholestan-3-one (37). The rates of 12a-hydroxylation of these C27-steroids differ considerably the rate with 5-cholestene-3/5,7a-diol is about one-tenth and with 5 -cholestane-3a,7a-diol about half of that with 7a-hydroxy-4-cholesten-3-one (37). Einarsson (37) and Suzuki et al. (38) have studied some properties of the 12a-hydroxylase system with special reference to the possible participation of electron carriers such as NADPH-cytochrome c reductase and cytochrome P-450. The 12a-hydroxylation of 7a-hydroxy-4-cholesten-3-one was inhibited by cytochrome c, indicating that NADPH-cytochrome c reductase might be involved. However, no direct evidence for the participation of flavins was obtained. If NADPH-cytochrome c reductase participates, it is not rate-limiting, since the activity of this enzyme increases upon treatment with thyroxine whereas the activity of the 12a-hydroxylase decreases (39). Suzuki et al. (38) found no inhibition of 12a-hydroxylation by carbon monoxide, whereas Einarsson (37) obtained some inhibition. The 12a-hydroxylase activity was unaffected by methylcholanthrene treatment (40) and lowered by phenobarbital treatment (37,38). These observations indicate that the cytochrome(s) P-450 induced by methylcholanthrene and... 

The calibration curves plotted from certain steroids after having sprayed with sulphuric acid, do not pass through the origin a small part of the film emulsion is always slightly altered for various reasons during development. The slopes of the calibration curves of the different individual compounds (steroids) differ as a result of differences in the intensity of the light emitted from the spots [316, 317]... 

A surprising observation is that certain alkyl ferrocenes are surface active, although we did not anticipate this. None of our compounds formed assemblies that could be readily characterized in the neutral state and the properties of the non-oxidized systems were not investigated further. In any event, the mono-steroidal ferrocene shown above did form vesicles. In this particular studythe half wave potentials for the ferrocenyl bis(amides) fell in the range 700-1000 mV. The mono-steroid differed from the other compounds in two important respects it was the only monosubstituted system studied and it was the only compound lacking an amide carbonyl group bonded directly to the ferrocene structure. The fact that it formed vesicles may be due to its lower halfwave potential, a structural difference attributable to the ether, rather than amide, linkage, or the presence of one, rather than two, steroids. No doubt all of these variations contribute to the success of the system. 

When you hear or read the word steroids, two things probably come to mind immediately athletes who take steroids illegally to develop their muscles, and the pill used for birth control. But what do you know about steroids aside from this general association What is their structure and function How does one steroid differ from another Where are they found in nature ... 

Classification.—Steroids differ so profoundly in their physiological activity that a chemical classification tends to obscure their practical... 

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