Identification of a new inborn error in bile acid synthesis: mutation of the oxysterol 7alpha-hydroxylase gene causes severe neonatal liver disease

We describe a metabolic defect in bile acid synthesis involving a deficiency in 7alpha-hydroxylation due to a mutation in the gene for the microsomal oxysterol 7alpha-hydroxylase enzyme, active in the acidic pathway for bile acid synthesis. The defect, identified in a 10-wk-old boy presenting with severe cholestasis, cirrhosis, and liver synthetic failure, was established by fast atom bombardment ionization-mass spectrometry, which revealed elevated urinary bile acid excretion, a mass spectrum with intense ions at m/z 453 and m/z 510 corresponding to sulfate and glycosulfate conjugates of unsaturated monohydroxy-cholenoic acids, and an absence of primary bile acids. Gas chromatography-mass spectrometric analysis confirmed the major products of hepatic synthesis to be 3beta-hydroxy-5-cholenoic and 3beta-hydroxy-5-cholestenoic acids, which accounted for 96% of the total serum bile acids. Levels of 27-hydroxycholesterol were > 4,500 times normal. The biochemical findings were consistent with a deficiency in 7alpha-hydroxylation, leading to the accumulation of hepatotoxic unsaturated monohydroxy bile acids. Hepatic microsomal oxysterol 7alpha-hydroxylase activity was undetectable in the patient. Gene analysis revealed a cytosine to thymidine transition mutation in exon 5 that converts an arginine codon at position 388 to a stop codon. The truncated protein was inactive when expressed in 293 cells. These findings indicate the quantitative importance of the acidic pathway in early life in humans and define a further inborn error in bile acid synthesis as a metabolic cause of severe cholestatic liver disease.

New method for determination of fecal sterols in urine using non-chlorinated solvents

A new method has been developed to determine a number of sterols in urine using non-chlorinated solvents, namely methyl tert.-butyl ether and methanol (the MTB method). The method involves liquid-liquid extraction, saponification, reextraction, silylation and final identification and quantification by GC-FID. The sterols determined were coprostanol, epicoprostanol, cholesterol and dihydrocholesterol. 5Alpha-cholestane was used as internal standard. The limit of detection for the sterols in this experiment was 2 microg l(-1) urine. Recovery of coprostanol over the range 5-100 microg l(-1) urine by this method was between 80 and 92%.

Biochemical studies of inherited diseases related to abnormal cholesterol metabolism. II: Absence of unusual C28 and C29 bile acid homologs in bile and urine of sitosterolemia

Bile acids, bile alcohols and sterols excreted in bile and urine from a patient with sitosterolemia were studied. Glycine- and taurine-conjugated cholic acid, deoxycholic acid and chenodeoxycholic acid were identified as the major constituents of both the bile and urine. Lesser amounts of unconjugated cholic acid and 3 alpha, 7 alpha, 12 alpha, 24-tetrahydroxy-5 beta-cholestan-26-oic acid were found in the bile, but cholic acid was the only unconjugated bile acid in the urine. Relatively high proportions of campesterol and sitosterol compared to cholesterol were excreted in the bile, while cholesterol was the only sterol detected in the urine. Bile alcohols were not detected in the bile, but the following bile alcohols were excreted in the urine as glucurono-conjugates: 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol; 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol; 5 beta-cholestane- 3 alpha,7 alpha,12 alpha,24,25-pentol; 5 beta-cholestane- 3 alpha,7 alpha,12 alpha,25,26-pentol. In neither the bile nor urine, were C28 and C29 bile acid homologs detected. Thus, the main route for the excretion of plant sterols in sitosterolemia is thought to be secretion into the bile as neutral sterols.

Bile acids. XXXV. Metabolism of 5 -cholestan-3 -ol in the Mongolian gerbil

The principal bile acid of Mongolian gerbil bile is cholic acid, although small amounts of chenodeoxycholic and lesser amounts of deoxycholic acids are identified. Muricholic acids were not found in gerbil bile. The ratio of trihydroxy to dihydroxy bile acids in gerbil bile is approximately 11:1. After administration of [4-(14)C]5alpha-cholestan-3beta-ol to gerbils with bile fistulas, 4-7% of the administered (14)C was recovered in bile and 16% in urine on the first 6 days. Alkaline hydrolysis of the bile afforded the biliary acids which were separated by partition chromatography. The (14)C ratio of trihydroxy to dihydroxy bile acids was 11:1. Allocholic acid was identified as the major acidic biliary metabolite. From analysis of (14)C retained in selected tissues, the adrenal gland appears to be an important site for retention of cholestanol or its metabolites.

The pattern of urinary excretion of individual 17-ketosteroids in rhesus monkeys

A systematic procedure for the extraction, separation, purification and colorimetric determination of urinary individual 17-ketosteroids in normal rhesus monkeys is described. Dehydroepiandrosterone was extracted after hot hydrolysis of the urine at neutral pH and the remaining steroid conjugates were extracted at pH 2 by the addition of ammonium sulphate. The liberated steroids were extracted after enzyme hydrolysis and the ketonic steroids were separated from the non-ketones by the Girard T reaction. The 11-deoxy steroids were separated from the 11-oxygenated steroids on a Celite column. They were further separated by paper chromatography and after elution, the individual 17-ketosteroids were estimated by the Zimmermann reaction. Normal mean excretion values in 30 female monkeys for total neutral 17-ketosteroids were 1.8 mg/24 h (range 1.5–2.6); total 17-hydroxycorticosteroids, 3.1 mg/24 h (range 2.2–4.8); androsterone, 38.6 μg/kg/24 h (range 9.3–60.2); aetiocholanolone, 19.2 μg/kg/24 h (range 6.8–30.7); dehydroepiandrosterone, 30.8 μg/kg/24 h (range 13.4–50.6); 11-ketoandrosterone, 7.5 μg/kg/24 h (range 5.1–14.1); 11-ketoaetiocholanolone, 10.2 μg/kg/24 h (range 6.8–18.3); 11β-hydroxyandrosterone, 15.4 μg/kg/24 h (range 8.8–26.7); 11β-hydroxyaetiocholanolone, 19.6 μg/kg/24 h (range 12.2–33.1). For total neutral 17-ketosteroids in 20 males, they were 2.5 mg/day (range 2.3–4.1); total 17-hydroxycorticosteroids, 3.7 mg/day (range 2.8–5.3); androsterone, 51.5 μg/kg/24 h (range 12.3–76.7); aetiocholanolone, 22.6 μg/kg/24 h (range 8.7–42.3); dehydroepiandrosterone, 41.3 μg/kg/24 h (range 16.9–59.7); 11-ketoandrosterone, 9.6 μg/kg/24 h (range 6.4–16.3); 11-ketoaetiocholanolone, 12.3 μg/kg/24 h (range 8.2–20.5); 11β-hydroxyandrosterone, 17.5 μg/kg/24 h (range 11.7–29.2); 11β-hydroxyaetiocholanolone, 21.7 μg/kg/24 h (range 14.5–36.4).

Urinary and biliary excretion of [4-14C]progesterone, [4-14C]20 alpha- and [4-14C]20 beta-hydroxypregn-4-en-3-one metabolities in the rabbit

[4-14C]Progesterone, [4-14C]20α- and 20β-hydroxypregn-4-en-3-one were injected intravenously into deeply anaesthetized rabbits and the bile and urine collected for 6 h. Neutral metabolites recovered after Ketodase hydrolysis of bile accounted for a mean of 82·8% (range 68·0–98·8%), 68·4% (61·0–80·0%) and 59·0% (57·0–61·0%) of the metabolites of progesterone, 20α-and20β-hydroxypregn-4-en-3-one, respectively. Acidic metabolites accounted for no more than 14·7% of the biliary radioactivity. Similar recoveries of neutral metabolites were obtained after hydrolysis of bile with 15% HCl, but only 41·0% (22·2–62·0%), 45·3% (36·4–55·4%) and 13·7% (10·6–16·9%) of the urinary metabolites were extractable as neutral metabolites. Acidic metabolites represented a further 33·9% (28·9–49·5%), 34·9% (27·5–40·4%) and 38·6% (29·4–47·8%) of the urinary radioactivity, respectively.

Neutral ether soluble metabolites more polar than 5β-pregnane-3α,20α-diol were the most abundant metabolites. 3α-Hydroxy-5β-pregnan-20-one was identified in the bile as a metabolite of [4-14C]progesterone whereas 20α-hydroxypregn-4-en-3-one was present in the urine. 5β-Pregnane-3α, 20α-diol was identified as a biliary metabolite of [4-14C]20β-hydroxypregn-4-en-3-one.

The gas-liquid chromatography of steroid formates; an application in congenital adrenal hyperplasia

The gas-liquid chromatography (GLC) of some C19 steroid formates has been investigated in an attempt to speed up the final stages of the estimation of the 11-oxygenation index. SE-30 was found to give the best separation of the urinary C19 steroids formed after borohydride reduction and periodate oxidation of urine. Formates, acetates, propionates, n-butyrates, valerates and trimethylsilyl ethers were examined; formate esters gave the best separation of androsterone and aetiocholanolone. Estimation of the 11-oxygenation index by GLC increases the specificity and speed of single estimations and it is suggested that this method may find use as a rapid screening test for abnormal urinary steroid patterns.

Some aspects of the measurement of cortisol production in patients with breast cancer

The production rate of cortisol based on both the plasma clearance of the hormone (plasma production rate) and the urinary metabolite method (urinary production rate) was simultaneously measured in early or advanced breast cancer patients and in controls. Higher production of the hormone was observed by both these methods in patients with advanced breast cancer.

There was a significant correlation between the plasma production rate of cortisol and its urinary production based on the specific activities of three urinary metabolites, namely, cortisol, tetrahydrocortisol (THF) and tetrahydrocortisone (THE). However, the values obtained for the urinary production rate differed considerably in about one-third of the patients due to differences in the specific activities of THE and THF. It is postulated that, in some cases, there may be a second precursor of urinary THE and THF which contributes significant amounts to the excretion of these metabolites.

No correlation was found between the cortisol production rate and urinary total 17-hydroxycorticosteroids (17-OHCS).

Distribution patterns of in vivo conversion products of injected estradiol-17-beta-4-14C and estrone-4-14C in the urines of the nonlaying and laying hen

Estradiol-17β-4-14C was injected into a mature hen when it was not in lay and when it was in lay. In each instance the major radioactive conversion products in the urine were estrone and estradiol-17α. The percentage of the total radioactive phenolic steroids present in the urine as estradiol-17β was higher, and the percentages present as estradiol-17α and as estrone were lower when the hen was not in lay than when the hen was in lay. Estrone-4-14C was injected into a mature hen in a second similar experiment, and the major radioactive conversion products in the urine were estradiol-17β and estradiol-17α. As in the first experiment, the percentage of the total radioactive phenolic steroids present in the urine as estradiol-17β was higher and the percentages present as estradiol-17α and as estrone were lower when the hen was not in lay than when she was in lay.Irrespective of whether estrone-4-14C or estradiol-17β-4-14C were injected, the major radioactive phenolic steroids in the urine were estradiol-17β, estrone, and estradiol-17α, in that order, when the hen was not in lay, and estrone and estradiol-17β or estradiol-17α, in that order, when the hen was in lay.

Estrogen conjugates of hen's urine

Estrone-6,7-3H and ornithine-5-14C were injected concurrently into a hen and the steroid-conjugated fractions of the urine subsequently excreted were examined for the presence of radioactive phenolic steroids. The results indicated that neither estrone-6,7-3H nor its phenolic in vivo conversion products were excreted as conjugates with ornithine. Possible biliary excretion of such conjugate(s), however, was not excluded by the experiment.

Esterification of injected epicoprostanol in a human subject

That a necessary requirement for in vivo esterification of 3-hydroxy sterols is the equatorial conformation of the hydroxyl group has been substantiated by the administration of epicoprostanol-3-(3)H (3-OH equatorial) to a man with a complete biliary fistula. Radioactive epicoprostanol was identified in both free and esterified sterols of plasma. The specific activity of biliary sterols was much higher than that of plasma sterols; this indicated a preferential removal of epicoprostanol from circulating sterols. The appearance of tritium in body water demonstrated that a portion of the labeled epicoprostanol underwent oxidation at C-3.

Formation of ring-D-hydroxylated estrogens from C-19 precursors administered to the fetus in utero

Two studies were performed on the origin of ring-D-hydroxylated estrogens during late pregnancy using an experimental design in which the labeled substrates were introduced into the fetus during transfusion in utero for erythroblastosis fetalis. Maternal urine was then collected for 5 days and estriol, 15α-hydroxyestradiol, and 15α-hydroxyestriol were isolated following Glusulase hydrolysis of the urinary conjugates. From the radioactivity present in each urinary metabolite expressed as a percentage of that excreted, it was possible to conclude that a large amount of dehydroisoandrosterone sulfate was converted to estriol and smaller amounts to 15α-hydroxyestradiol and 15α-hydroxyestriol. In addition, 15α-hydroxyandrostenedione was converted to 15α-hydroxyestriol in better yields than to 15α-hydroxyestrad-iol. These findings suggest that 15α-hydroxylated estrogens found in late pregnancy urine can be derived from neutral precursors in the fetus. It was also apparent that a sequence of hydroxylation, 15α followed by 16α, occurs in the formation of 15α-hydroxyestriol but it is uncertain whether 16α hydroxylation occurs prior to, or after, aromatization.

Urinary conversion products of injected progesterone-4-14C in the domestic fowl

Progesterone-4-14C was administered intramuscularly to hens. The urine subsequently excreted contained radioactive 5β-pregnane-3α,20β-diol and 5β-pregnan-3α-ol-20-one, the identities being established by thin-layer chromatographic mobilities of the isolated materials and derivatives thereof, and by crystallization of the alcohols and their acetates to constant specific activity with reference carrier materials. Radioactive progesterone was not detected in the urine, neither did the results provide any evidence for the presence of radioactive 5α-pregnane derivatives.