Role of a disordered steroid metabolome in the elucidation of sterol and steroid biosynthesis.

In 1937 Butler and Marrian found large amounts of the steroid pregnanetriol in urine from a patient with the adrenogenital syndrome, a virilizing condition known to be caused by compromised adrenal secretion even in this pre-cortisol era. This introduced the concept of the study of altered excretion of metabolites as an in vivo tool for understanding sterol and steroid biosynthesis. This approach is still viable and has experienced renewed significance as the field of metabolomics. From the first cyclized sterol lanosterol to the most downstream product estradiol, there are probably greater than 30 steps. Based on a distinctive metabolome clinical disorders have now been attributed to about seven post-squalene cholesterol (C) biosynthetic steps and around 15 en-route to steroid hormones or needed for further metabolism of such hormones. Forty years ago it was widely perceived that the principal steroid biosynthetic defects were known but interest rekindled as novel metabolomes were documented. In his career this investigator has been involved in the study of many steroid disorders, the two most recent being P450 oxidoreductase deficiency and apparent cortisone reductase deficiency. These are of interest as they are due not to mutations in the primary catalytic enzymes of steroidogenesis but in ancillary enzymes needed for co-factor oxido-reduction A third focus of this researcher is Smith-Lemli-Opitz syndrome (SLOS), a cholesterol synthesis disorder caused by 7-dehydrocholesterol reductase mutations. The late George Schroepfer, in whose honor this article has been written, contributed greatly to defining the sterol metabolome of this condition. Defining the cause of clinically severe disorders can lead to improved treatment options. We are now involved in murine gene therapy studies for SLOS which, if successful could in the future offer an alternative therapy for this severe condition.

The value of estimated GFR in comparison to measured GFR for the assessment of renal function in adult patients with Fabry disease.

BACKGROUND: Renal disease is one of the major complications in Fabry disease, an X-linked lysosomal storage disease due to deficiency of the enzyme alpha-galactosidase A. The aim of our study was to determine the value of creatinine-, cystatin C- and beta-trace-based formulas for the estimation of glomerular filtration rate (eGFR) in Fabry patients. For comparison, the gold standard method (125)I-labelled iothalamate/(131)I-labelled hippuran [measured GFR (mGFR)] was used. METHODS: GFR was estimated by using 11 different formulas based on creatinine, cystatin C and beta-trace protein. Accuracy and precision, detection of early decline of renal function and follow-up of renal function by eGFR was compared to mGFR. RESULTS: One hundred and thirty-six GFR measurements and plasma samples were available from 36 (20 male) Fabry patients, treated with agalsidase alpha or beta with a median follow-up of 3.1 (range 1.5-5.2) years. Median mGFR was 97.3 (15.5-148.6) ml/min/1.73 m(2) in males and 84.4 (23.0-131.0) ml/min/1.73 m(2) in females at the start of follow-up. CONCLUSIONS: Although none of the investigated endogenous markers proved to be an equivalent substitute for mGFR in Fabry patients, the Stevens equation, a creatinine- and cystatin C-based formula, most closely approximated the mGFR. When a creatinine-based formula is preferred, considering that there is no standardized method available for cystatin C, the abbreviated Modification of Diet in Renal Disease (aMDRD) and the recently developed Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas had the best performance. In male Fabry patients, the aMDRD may overestimate GFR, especially in the higher ranges. In these cases, CKD-EPI may perform better.

Application of comprehensive two-dimensional gas chromatography to sterols analysis.

The applicability of comprehensive two-dimensional gas chromatography (GCxGC) for sterol analysis was investigated by separation and identification of endogenous sterols in standards, and spiked in human urine. The modulation temperature was optimized to achieve the best separation and signal enhancement. The separation pattern of trimethylsilyl (TMS) derivatives of sterols was compared on two complementary column sets. Whilst the BPX5/BPX50 column set offers better overall separation, BPX50/BPX5 provides better peak shape and sensitivity. Comparison of the identification power of GCxGC-TOFMS against both the NIST05 MS library and a laboratory created (in-house) TOFMS library was carried out on a free sterols extract of urine, derivatised and spiked at the World Anti-Doping Agency (WADA) limit of 2 ng mL(-1). The average match quality for 19 analysed sterols on the BPX50/BPX5 column set was 950/1000 when searched against the in-house library; only four were identified against the NIST05 library, at a match threshold of 800. The match quality of GCxGC-TOFMS spectra was superior to that for analysis using 1D GC-TOFMS for sterols spiked in urine at 10 ng mL(-1). An r(2)>0.997 was obtained for the concentration range between 0.25 ng mL(-1) and 10 ng mL(-1) for three selected sterols. The lowest limit of detection (LOD) was obtained for estrone (0.1 ng mL(-1)) and the highest LOD was for 5alpha-androstan-3alpha,11beta-diol-17-one, epitestosterone and cholesteryl butyrate (1 ng mL(-1)), using a match threshold of at least 800 and signal-to-noise ratio of at least 10. TOFMS coupled to GCxGC enabled satisfactory identification of sterols in urine at their LOD. A minimum acceptable match (MAM) criterion for urinary sterols using 2D retention times and TOF mass spectra is introduced. This study shows that GCxGC-TOFMS yields high specificity for steroids derived from urine, with detection limits appropriate for use in doping control.

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.

[Steroid balance in breast cancers of varying histological structure]. / Steroidnyi balans u bol'nykh rakom molochnoi zhelezy razlichnoi gistostruktury.

Patients with breast cancer in stage I--II of various histological structure showed varied hormonal disturbances. In adenocarcinoma a high level of classic estrogens or total phenolsteroids was noted. In low differentiated cancers (solid, scirrhus) the values of estrogens excretion were considerably lower, but, if correlated with other hormones (androsterone), a relative hyperestrogenization is observed. Scirrhous cancers are characterized by the increased 17-ketogenic steroids excretion. The character of hormonal disturbances concomitant with the predominant development of certain breast tumor structures (adenocarcinoma, solid cancer, scirrhus) is identical for the patients being in their reproductive and menopausal period.

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.