Progesterone radioactive

These discoveries generated a lot of effort over the successive 25 years in the preparation of especially designed drug delivery systems for the controlled release of radioactive progesterone [654], colchicine [656], naproxen [657,673, 674], mitomycin C [675-677], inulin [678], trimethoprin [657], succinylsul-fathiazole [657], ethacrynic acid [653], and steroids [633], regardless of whether these drugs are physically trapped in polyphosphazene matrices, or chemically bonded to the polymer skeleton. 

FIGURE 5 Erosion release profile for radioactive progesterone from a a mixed-substituent imidazolyl/p-methylphenoxyphosphazene polymer. 31.)... 

Figure 3.22 Release rate of radioactive progesterone from an erodable matrix of a poly(imida-zolyl-aryloxy)phosphazene polymer. From Laurencin, Koh, Neenan, Allcock, and Langer, reference 197.

The substrate, pregnenolone (158 nmol) dissolved in propylene glycol, was added to the incubation flask containing the enzyme preparation and NAD in a final volume of 5 mL. After an incubation period of 60 minutes, the reaction was terminated by addition of 15 fiL of dichloromethane, and radioactive progesterone was added as a recovery standard. The organic phase was recovered, dried, and redissolved in 70% ethanol, and a sample was analyzed by HPLC. Figure 9.81 shows an analysis of an incubation mixture with and without incubation with the ovarian preparation. The substrate (not seen) is converted exclusively to progesterone. 

Although automated hnmunoassays are less labor intensive than RIAs and yield results in less time without the need for radioactivity, these assays do not have adequate functional sensitivity for appUcations involving low progesterone concentrations (i.e., men, postmenopausal women, and children). Taieb and co-workers analyzed the detection limits and functional sensitivities for eight automated progesterone... 

A further structural class is represented by compounds of the type 56 [75, 76]. These compounds have only been characterized by their inhibitory effect on the binding of radioactively labeled progesterone at a standard concentration of 200 nM. A key component in this series is the acceptor group (e.g. N02, CN or Cl) at the aryl group... 

It has been shown that the fetal adrenal can convert progesterone and pregnenolone into cortisol in substantial yield (Sections 4.2.1 and 4.2.2), and, notably, Solomon (S25), after perfusion of fetuses with proges-terone-4- C, has isolated radioactive corticosterone and cortisol from the... 

The mass balance approach was used to develop an in vivo animal model for skin penetration of topically applied dmgs in hairless rats (Simonsen et al., 2002). Two dmgs, C-sahcylic acid and C-butyl salicylate were topically applied for the assessment of the model. Rapid and differentiated percutaneous absorption of both compounds was indicated by urinary excretion data. Total mass balance on the applied radioactivity was performed, and 90% recovery was achieved. Carver and Riviere (1989) conducted an extensive mass balance study with " C-labeled xeno-biotics after topical and intravenous administration to pigs. These authors reported that dermal absorption of C-benzoic acid, caffeine, malathion, parathion, progesterone, and testosterone was 25.7, 11.8, 5.2, 6.7, 16.2, and 8.8%, respectively, following topical administration to pigs. 

The amount of progesterone was calculated by extracting labeled progesterone from groups of 2, 3, or 5 oocytes at the times listed. Radioactivity was determined in a Packard liquid scintillation spectrometer with external standardization. The quench-corrected counts were then used to calculate the amount of progesterone. 

With uptake of H- or C-labeled progesterone just sufficient to induce all of the oocytes to mature, radioactivity associated with progesterone decreased rapidly, resulting in barely detectable levels within 6-8 hours, i.e., 4-6 hours before any visible signs of GV breakdown. Associated with the loss of progesterone was the concomitant appearance of three additional major areas of radioactivity a less polar peak (Mi) detectable within 10 minutes, and two more polar peaks detectable soon thereafter (Fig. 7). 

There is little question that the site of steroid conversions is intracellular. Complete removal of follicle cells which remain adherent to oocytes after manual dissection from their follicles does not alter chromatographic profiles, either quantitatively or qualitatively. Likewise, the profiles obtained from oocytes injected with radioactive progesterone were essentially identical to those obtained by incubation of oocytes with exogenous hormone. Thus, the observations reveal a heretofore unsuspected capability of oocytes to participate in steroid metabolism. This is not restricted to Bana pipiens, but also has been observed in Xenopus laevis and Rana catesbiana. Likewise, both exogenous deoxycorticosterone and estradiol are metabolized by isolated oocytes, giving rise to different kinds of metabolites than obtained with progesterone (Reynhout and Smith, 1973). 

Fig. 7. Progesterone metabolism by oocytes of Rana pipens. Thin-layer chromatographic profiles of radioactivity in oocytes and in the medium at various times after exposure to [ H]progesterone at 1 Ag/ml for 15 minutes. The diagram below each profile shows the position of progesterone spot, origin (marked with an X), and solvent front. Mi and M are the metabolite peaks referred to in the text. See Reynhout and Smith (1973) for additional information.

In the case of a nonenzyme protein, such as a steroid receptor, requirements of homogeneity, amounts of protein necessary, and absence of the activity handle pose additional problems. We have tried to affinity label partially purified progesterone receptor wdth O Malley s 30% ammonium sulfate fraction from chick oviduct and bromoacetoxyproges-terones. On subsequent sucrose density gradient analysis, w e observed several radioactive peaks. Obviously, further purification is a prerequisite to intensive study. 

To determine the optimal concentration of cyclic AMP for maximum stimulation of steroidogenesis, graduated doses from 0.002M to 0.04M cyclic AMP were added to separate vessels containii acetate-l- C and slices from a single corpus luteum. Progesterone synthesis was assessed spectrophotometrically and by the incorporation of radioactivity. The results are illustrated in Fig. 2. As the concentration of cyclic AMP was increased, the synthesis of progesterone (assessed by both parameters) was increased. A maximum was reached at 100 pmoles per 5 ml of medium or 0.02M cyclic AMP. 

Metabolic studies with progesterone-2l-C in rodents showed that approximately 10% of the radioactivity was expired as CO2. About 80% of the radioactivity was in the combined excreta and the majority of this in the feces. In bile fistula animals the radioactivity was in the bile this suggests that most of the fecal activity was introduced into the intestines of the normal animals by way of the bile. However, one must again be reminded of species variation, and it is apparent that much work remains to be done in this important area. 

Followdng the intravenous injection of labeled progesterone, about 40% of the radioactivity is excreted in the bile of the rabbit and only 20% in... 

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