W

HC7 11

H3C 0 0

Isopentenyl pyrophosphate (1)

Juvenile hormone (insect hormone)

Plastoquinones Abscisic acid Gibberellic acid

Plant hormones

FIGURE 2-1 Representative isoprenoids that may be derived from isopentenyl pyrophosphate and dimethylallyl pyrophosphate.

raphy (HPLC) or gas chromatography, combined with the use of continuous on-line monitoring by mass spectrometry with computer-assisted data storage and analysis, frequently permit unequivocal structural determinations on impure samples that contain less than 1 ng of the steroid of interest.

An equally important contribution to our present understanding of the biochemistry of steroids was the introduction and general availability of radioactively labeled compounds. Radioactive steroids offer two major advantages: The presence of the radioactive label (a) provides a significant increase in the sensitivity of detection of the steroid under study (prior to the advent of radioactive steroids, investigators relied upon colorimetric or bioassay procedures to quantitate the steroid of interest) and (b) allows the investigator to detect, from either in vivo whole animal or in vitro experiments with perfused organs, tissue slices, cell suspensions, cell homogenates, or purified enzyme preparations, the presence of new compounds that otherwise would be unappreciated. Thus, it was through the application of radioisotope techniques, modern procedures of chromatography, and structure determination that whole categories of new steroid hormones were discovered [for example, vitamin D metabolites (Chapter 9) and catechol estrogens (Chapter 13)].

Phenanthrene (4) H

/CH, I H2C ^-C^ h i h i /CH2 I .C i C^ H2C c I c I I I H I H

H2C C CH2

CH2 j CH2 H

Cyclopentanoperhydrophenanthrene isterane) (5)

-CH2 ch2

Sterane (6) FIGURE 2-2 Parent ring structures of steroids.

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Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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