Radioimmunoassay of cortisone in serum, urine, and saliva to assess the status of the cortisol-cortisone shuttle.

We have developed a new assay for cortisone (E) in serum, saliva, and urine involving Celite chromatography followed by RIA with 125I-labeled E and scintillation proximity assay. The chromatography step separates cortisol (F) from E, and in combination with their RIAs, permits assessment of the status of the F-E shuttle. We report the results of basal, postcorticotropin (ACTH), and postdexamethasone E and F concentrations and their circadian fluctuations in the serum, saliva, and urine of healthy volunteers.

Convenient chromatographic prepurification step before measurement of urinary cortisol by radioimmunoassay.

We applied various prepurification protocols (extraction with different solvents, liquid/solid separation on bonded silica media, Celite, and Sephadex LH20 chromatography) with a range of commercially available RIA kits to measure cortisol in urine samples. We then compared the results with the concentrations measured by a HPLC method validated with reference to isotope dilution gas chromatography-mass spectrometry. We conclude that chromatography on a commercial, prepacked diol minicolumn (Waters Sep-Pak Vac RC) in combination with dichloromethane extraction is a convenient and very effective purification step before RIA of urinary cortisol in patients not receiving corticoid medication.

Depletion of histidine and tryptophan serum levels in porphyria cutanea tarda and congenital erythropoietic porphyria patients after irradiation with visible light.

We have studied the photosensitized oxidation, via singlet oxygen production, of histidine (His) and tryptophan (Trp) in the serum of porphyria patients and in the serum of healthy volunteers before or after addition of hematoporphyrin. It was observed that free plasma His and Trp are good probes of singlet oxygen production in the blood under visible light irradiation. However, Trp, which is mostly bound to serum albumin, is much less susceptible to photooxidation than His, which remains free in the plasma.